Infectious Diseases

New research is shedding light on how an infection with COVID-19 may reactivate, or even cause, psoriasis. 

 Psoriasis has several well-established triggers, including stress, skin injury, cold or warm air, and allergies. Illnesses like strep throat can also cause a psoriasis flare in some people – and it appears COVID may also do so. “Psoriasis flares have long been associated with bacterial and viral infections, particularly a form of psoriasis called guttate, which is characterized by tons of tiny red scaly bumps all over the body,” said Joel M. Gelfand, MD, a professor of dermatology and epidemiology at the University of Pennsylvania, Philadelphia. “Infection with COVID-19 has been associated with flares of guttate and pustular psoriasis, and even psoriasis that affects 100% of the skin ... in many published case reports.”

Israeli researchers recently found that psoriasis patients have a slightly higher risk of getting COVID,  although they are not at higher risk of hospitalization or death, which could be related to treatment with immune-modulating therapy, which can increase their risk of infections.
 

How could COVID cause psoriasis to flare? 

Psoriasis is an autoimmune condition, and inflammation can cause symptoms.

Investigators for a study from Albany (N.Y.) Medical College and Weirton (Pa.) Medical Center found that people in the study who were already diagnosed with the skin condition had an unexpected flare within a week to a month after testing positive for COVID. New psoriasis after a COVID infection was also found. The researchers think this could be because COVID causes inflammation in the body, which negatively affects previously well-controlled psoriasis. They also think it’s possible that COVID-related inflammation could trigger a genetic tendency to have psoriasis, which may explain why it can appear for the first time after a positive test.

“A viral infection like COVID-19 can signal the release of proinflammatory factors that can appear as rashes, such as with psoriasis.” said Robert O. Carpenter, MD, director of wellness at Texas A&M University in Bryan.
 

What are the symptoms of COVID-related psoriasis?

The signs are the same as those of any form of psoriasis.
 

For a patient with psoriasis, will COVID automatically make it worse?

Not necessarily.

“Psoriasis is a common condition, so people should be aware that new psoriasis that develops may not be related to COVID-19,” said Esther Freeman MD, PhD, director of global health dermatology at Massachusetts General Hospital in Boston.

As with every aspect of COVID, doctors and scientists are still learning about how serious and widespread a problem psoriasis after COVID-19 may be. “We have seen case reports that psoriasis can flare after COVID-19,” said Dr. Freeman, who is also an associate professor of dermatology at Harvard Medical School. “I will say, this has not been a tidal wave – more like sporadic cases here and there. So I do not think psoriasis flares are a major post-COVID finding, nor do they necessarily mean you have long COVID. That being said, we know that many different infections can cause psoriasis flares, and so, in that respect, it’s not that surprising that SARS-CoV-2, like other infections, could trigger a psoriasis flare.”

Could getting COVID more than once cause psoriasis to flare? It’s possible.

“Your body can change after having COVID-19,” said Dr. Carpenter. “We don’t know the long-term implications, but having COVID-19 repeatedly can increase the risk of long COVID, which can cause many systemic changes in your body.” 

Another important point: For patients who take biologics for treating psoriasis, getting vaccinated and boosted for COVID is an important step to take to help protect themselves.
 

Is psoriasis itself a potential symptom of COVID? 

“Yes, but we don’t know the frequency at which this may occur, and a causal relationship is difficult to establish from just case reports,” said Dr. Gelfand, who’s also medical director of the clinical studies unit in the department of dermatology at his university. “Typically, if a patient presents with a flare of psoriasis, particularly guttate, pustular, or erythrodermic forms, an infectious trigger should be considered, and testing for strep and possibly COVID-19 may be appropriate.”
 

A version of this article first appeared on Medscape.com.

New research is shedding light on how an infection with COVID-19 may reactivate, or even cause, psoriasis. 

 Psoriasis has several well-established triggers, including stress, skin injury, cold or warm air, and allergies. Illnesses like strep throat can also cause a psoriasis flare in some people – and it appears COVID may also do so. “Psoriasis flares have long been associated with bacterial and viral infections, particularly a form of psoriasis called guttate, which is characterized by tons of tiny red scaly bumps all over the body,” said Joel M. Gelfand, MD, a professor of dermatology and epidemiology at the University of Pennsylvania, Philadelphia. “Infection with COVID-19 has been associated with flares of guttate and pustular psoriasis, and even psoriasis that affects 100% of the skin ... in many published case reports.”

Israeli researchers recently found that psoriasis patients have a slightly higher risk of getting COVID,  although they are not at higher risk of hospitalization or death, which could be related to treatment with immune-modulating therapy, which can increase their risk of infections.
 

How could COVID cause psoriasis to flare? 

Psoriasis is an autoimmune condition, and inflammation can cause symptoms.

Investigators for a study from Albany (N.Y.) Medical College and Weirton (Pa.) Medical Center found that people in the study who were already diagnosed with the skin condition had an unexpected flare within a week to a month after testing positive for COVID. New psoriasis after a COVID infection was also found. The researchers think this could be because COVID causes inflammation in the body, which negatively affects previously well-controlled psoriasis. They also think it’s possible that COVID-related inflammation could trigger a genetic tendency to have psoriasis, which may explain why it can appear for the first time after a positive test.

“A viral infection like COVID-19 can signal the release of proinflammatory factors that can appear as rashes, such as with psoriasis.” said Robert O. Carpenter, MD, director of wellness at Texas A&M University in Bryan.
 

What are the symptoms of COVID-related psoriasis?

The signs are the same as those of any form of psoriasis.
 

For a patient with psoriasis, will COVID automatically make it worse?

Not necessarily.

“Psoriasis is a common condition, so people should be aware that new psoriasis that develops may not be related to COVID-19,” said Esther Freeman MD, PhD, director of global health dermatology at Massachusetts General Hospital in Boston.

As with every aspect of COVID, doctors and scientists are still learning about how serious and widespread a problem psoriasis after COVID-19 may be. “We have seen case reports that psoriasis can flare after COVID-19,” said Dr. Freeman, who is also an associate professor of dermatology at Harvard Medical School. “I will say, this has not been a tidal wave – more like sporadic cases here and there. So I do not think psoriasis flares are a major post-COVID finding, nor do they necessarily mean you have long COVID. That being said, we know that many different infections can cause psoriasis flares, and so, in that respect, it’s not that surprising that SARS-CoV-2, like other infections, could trigger a psoriasis flare.”

Could getting COVID more than once cause psoriasis to flare? It’s possible.

“Your body can change after having COVID-19,” said Dr. Carpenter. “We don’t know the long-term implications, but having COVID-19 repeatedly can increase the risk of long COVID, which can cause many systemic changes in your body.” 

Another important point: For patients who take biologics for treating psoriasis, getting vaccinated and boosted for COVID is an important step to take to help protect themselves.
 

Is psoriasis itself a potential symptom of COVID? 

“Yes, but we don’t know the frequency at which this may occur, and a causal relationship is difficult to establish from just case reports,” said Dr. Gelfand, who’s also medical director of the clinical studies unit in the department of dermatology at his university. “Typically, if a patient presents with a flare of psoriasis, particularly guttate, pustular, or erythrodermic forms, an infectious trigger should be considered, and testing for strep and possibly COVID-19 may be appropriate.”
 

A version of this article first appeared on Medscape.com.

New research is shedding light on how an infection with COVID-19 may reactivate, or even cause, psoriasis. 

 Psoriasis has several well-established triggers, including stress, skin injury, cold or warm air, and allergies. Illnesses like strep throat can also cause a psoriasis flare in some people – and it appears COVID may also do so. “Psoriasis flares have long been associated with bacterial and viral infections, particularly a form of psoriasis called guttate, which is characterized by tons of tiny red scaly bumps all over the body,” said Joel M. Gelfand, MD, a professor of dermatology and epidemiology at the University of Pennsylvania, Philadelphia. “Infection with COVID-19 has been associated with flares of guttate and pustular psoriasis, and even psoriasis that affects 100% of the skin ... in many published case reports.”

Israeli researchers recently found that psoriasis patients have a slightly higher risk of getting COVID,  although they are not at higher risk of hospitalization or death, which could be related to treatment with immune-modulating therapy, which can increase their risk of infections.
 

How could COVID cause psoriasis to flare? 

Psoriasis is an autoimmune condition, and inflammation can cause symptoms.

Investigators for a study from Albany (N.Y.) Medical College and Weirton (Pa.) Medical Center found that people in the study who were already diagnosed with the skin condition had an unexpected flare within a week to a month after testing positive for COVID. New psoriasis after a COVID infection was also found. The researchers think this could be because COVID causes inflammation in the body, which negatively affects previously well-controlled psoriasis. They also think it’s possible that COVID-related inflammation could trigger a genetic tendency to have psoriasis, which may explain why it can appear for the first time after a positive test.

“A viral infection like COVID-19 can signal the release of proinflammatory factors that can appear as rashes, such as with psoriasis.” said Robert O. Carpenter, MD, director of wellness at Texas A&M University in Bryan.
 

What are the symptoms of COVID-related psoriasis?

The signs are the same as those of any form of psoriasis.
 

For a patient with psoriasis, will COVID automatically make it worse?

Not necessarily.

“Psoriasis is a common condition, so people should be aware that new psoriasis that develops may not be related to COVID-19,” said Esther Freeman MD, PhD, director of global health dermatology at Massachusetts General Hospital in Boston.

As with every aspect of COVID, doctors and scientists are still learning about how serious and widespread a problem psoriasis after COVID-19 may be. “We have seen case reports that psoriasis can flare after COVID-19,” said Dr. Freeman, who is also an associate professor of dermatology at Harvard Medical School. “I will say, this has not been a tidal wave – more like sporadic cases here and there. So I do not think psoriasis flares are a major post-COVID finding, nor do they necessarily mean you have long COVID. That being said, we know that many different infections can cause psoriasis flares, and so, in that respect, it’s not that surprising that SARS-CoV-2, like other infections, could trigger a psoriasis flare.”

Could getting COVID more than once cause psoriasis to flare? It’s possible.

“Your body can change after having COVID-19,” said Dr. Carpenter. “We don’t know the long-term implications, but having COVID-19 repeatedly can increase the risk of long COVID, which can cause many systemic changes in your body.” 

Another important point: For patients who take biologics for treating psoriasis, getting vaccinated and boosted for COVID is an important step to take to help protect themselves.
 

Is psoriasis itself a potential symptom of COVID? 

“Yes, but we don’t know the frequency at which this may occur, and a causal relationship is difficult to establish from just case reports,” said Dr. Gelfand, who’s also medical director of the clinical studies unit in the department of dermatology at his university. “Typically, if a patient presents with a flare of psoriasis, particularly guttate, pustular, or erythrodermic forms, an infectious trigger should be considered, and testing for strep and possibly COVID-19 may be appropriate.”
 

A version of this article first appeared on Medscape.com.

The U.S. Food and Drug Administration (FDA) has approved the first vaccine for respiratory syncytial virus (RSV) in the United States, the agency announced May 3. Arexvy, manufactured by GSK, is the world’s first RSV vaccine for adults aged 60 years and older,the company said in an announcement.

Every year, RSV is responsible for 60,000–120,000 hospitalizations and 6,000–10,000 deaths among U.S. adults older than age, according to the FDA. Older adults with underlying health conditions — such as diabetes, a weakened immune system, or lung or heart disease — are at high risk for severe disease. "Today’s approval of the first RSV vaccine is an important public health achievement to prevent a disease which can be life-threatening and reflects the FDA’s continued commitment to facilitating the development of safe and effective vaccines for use in the United States," said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, in a statement.

The FDA approval of Arexvy was based on a clinical study of approximately 25,000 patients. Half of these patients received Arexvy, while the other half received a placebo. Researchers found that the RSV vaccine reduced RSV-associated lower respiratory tract disease (LRTD) by nearly 83% and reduced the risk of developing severe RSV-associated LRTD by 94%. The most commonly reported side effects were injection site pain, fatigue, muscle pain, headache, and joint stiffness/pain. Ten patients who received Arexvy and four patients who received placebo experienced atrial fibrillation within 30 days of vaccination. The company is planning to assess risk for atrial fibrillation in postmarking studies, the FDA said. The European Medicine Agency’s Committee for Medicinal Products for Human Use recommended approval of Arexvy on April 25, 2023, on the basis of data from the same clinical trial.

GSK said that the U.S. launch of Arexvy will occur sometime in the fall before the 2023/2024 RSV season, but the company did not provide exact dates. "Today marks a turning point in our effort to reduce the significant burden of RSV," said GSK’s chief scientific officer, Tony Wood, PhD, in a company statement. "Our focus now is to ensure eligible older adults in the U.S. can access the vaccine as quickly as possible and to progress regulatory review in other countries."

A version of this article first appeared on Medscape.com.

The U.S. Food and Drug Administration (FDA) has approved the first vaccine for respiratory syncytial virus (RSV) in the United States, the agency announced May 3. Arexvy, manufactured by GSK, is the world’s first RSV vaccine for adults aged 60 years and older,the company said in an announcement.

Every year, RSV is responsible for 60,000–120,000 hospitalizations and 6,000–10,000 deaths among U.S. adults older than age, according to the FDA. Older adults with underlying health conditions — such as diabetes, a weakened immune system, or lung or heart disease — are at high risk for severe disease. "Today’s approval of the first RSV vaccine is an important public health achievement to prevent a disease which can be life-threatening and reflects the FDA’s continued commitment to facilitating the development of safe and effective vaccines for use in the United States," said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, in a statement.

The FDA approval of Arexvy was based on a clinical study of approximately 25,000 patients. Half of these patients received Arexvy, while the other half received a placebo. Researchers found that the RSV vaccine reduced RSV-associated lower respiratory tract disease (LRTD) by nearly 83% and reduced the risk of developing severe RSV-associated LRTD by 94%. The most commonly reported side effects were injection site pain, fatigue, muscle pain, headache, and joint stiffness/pain. Ten patients who received Arexvy and four patients who received placebo experienced atrial fibrillation within 30 days of vaccination. The company is planning to assess risk for atrial fibrillation in postmarking studies, the FDA said. The European Medicine Agency’s Committee for Medicinal Products for Human Use recommended approval of Arexvy on April 25, 2023, on the basis of data from the same clinical trial.

GSK said that the U.S. launch of Arexvy will occur sometime in the fall before the 2023/2024 RSV season, but the company did not provide exact dates. "Today marks a turning point in our effort to reduce the significant burden of RSV," said GSK’s chief scientific officer, Tony Wood, PhD, in a company statement. "Our focus now is to ensure eligible older adults in the U.S. can access the vaccine as quickly as possible and to progress regulatory review in other countries."

A version of this article first appeared on Medscape.com.

The U.S. Food and Drug Administration (FDA) has approved the first vaccine for respiratory syncytial virus (RSV) in the United States, the agency announced May 3. Arexvy, manufactured by GSK, is the world’s first RSV vaccine for adults aged 60 years and older,the company said in an announcement.

Every year, RSV is responsible for 60,000–120,000 hospitalizations and 6,000–10,000 deaths among U.S. adults older than age, according to the FDA. Older adults with underlying health conditions — such as diabetes, a weakened immune system, or lung or heart disease — are at high risk for severe disease. "Today’s approval of the first RSV vaccine is an important public health achievement to prevent a disease which can be life-threatening and reflects the FDA’s continued commitment to facilitating the development of safe and effective vaccines for use in the United States," said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, in a statement.

The FDA approval of Arexvy was based on a clinical study of approximately 25,000 patients. Half of these patients received Arexvy, while the other half received a placebo. Researchers found that the RSV vaccine reduced RSV-associated lower respiratory tract disease (LRTD) by nearly 83% and reduced the risk of developing severe RSV-associated LRTD by 94%. The most commonly reported side effects were injection site pain, fatigue, muscle pain, headache, and joint stiffness/pain. Ten patients who received Arexvy and four patients who received placebo experienced atrial fibrillation within 30 days of vaccination. The company is planning to assess risk for atrial fibrillation in postmarking studies, the FDA said. The European Medicine Agency’s Committee for Medicinal Products for Human Use recommended approval of Arexvy on April 25, 2023, on the basis of data from the same clinical trial.

GSK said that the U.S. launch of Arexvy will occur sometime in the fall before the 2023/2024 RSV season, but the company did not provide exact dates. "Today marks a turning point in our effort to reduce the significant burden of RSV," said GSK’s chief scientific officer, Tony Wood, PhD, in a company statement. "Our focus now is to ensure eligible older adults in the U.S. can access the vaccine as quickly as possible and to progress regulatory review in other countries."

A version of this article first appeared on Medscape.com.

What do green monkeys, fruit bats, and python caves all have in common? All have been implicated in outbreaks as transmission sources of the rare but deadly Marburg virus. Marburg virus is in the same Filoviridae family of highly pathogenic RNA viruses as Ebola virus, and similarly can cause a rapidly progressive and fatal viral hemorrhagic fever.

In the first reported Marburg outbreak in 1967, laboratory workers in Marburg and Frankfurt, Germany, and in Belgrade, Yugoslavia, developed severe febrile illnesses with massive hemorrhage and multiorgan system dysfunction after contact with infected African green monkeys imported from Uganda. Since the first discovery of Marburg virus, there have been over 14 Marburg virus disease (MVD) outbreaks worldwide with nearly 600 cases and case fatality rates of 23%-90%.

The majority of MVD outbreaks have occurred in sub-Saharan Africa, and primarily in three African countries: Angola, the Democratic Republic of Congo, and Uganda. In sub-Saharan Africa, these sporadic outbreaks have had high case fatality rates (up to 80%-90%) and been linked to human exposure to the oral secretions or urinary/fecal droppings of Egyptian fruit bats (Rousettus aegyptiacus), the animal reservoir for Marburg virus. These exposures have primarily occurred among miners or tourists frequenting bat-infested mines or caves, including Uganda’s python cave, where Centers for Disease Control and Prevention investigators have conducted ecological studies on Marburg-infected bats. Person-to-person transmission occurs from direct contact with the blood or bodily fluids of an infected person or contact with a contaminated object (for example, unsterilized needles and syringes in a large nosocomial outbreak in Angola).

On April 6, 2023, the CDC issued a Health Advisory for U.S. clinicians and public health departments regarding two separate MVD outbreaks in Equatorial Guinea and Tanzania. These first-ever MVD outbreaks in both West and East African countries appear to be epidemiologically unrelated. As of March 24, 2023, in Equatorial Guinea, a total of 15 confirmed cases, including 11 deaths, and 23 probable cases, all deceased, have been identified in multiple districts since the outbreak declaration in February 2023. In Tanzania, a total of eight cases, including five deaths, have been reported among villagers in a northwest region since the outbreak declaration in March 2023. While so far cases in the Tanzania MVD outbreak have been epidemiologically linked, in Equatorial Guinea some cases have no identified epidemiological links, raising concern for ongoing community spread.

To date, no cases in these outbreaks have been reported in the United States or outside the affected countries. Overall, the risk of MVD in nonendemic countries, like the United States, is low but there is still a risk of importation. As of May 2, 2023, CDC has issued a Level 2 travel alert (practice enhanced precautions) for Marburg in Equatorial Guinea and a Level 1 travel watch (practice usual precautions) for Marburg in Tanzania. Travelers to these countries are advised to avoid nonessential travel to areas with active outbreaks and practice preventative measures, including avoiding contact with sick people, blood and bodily fluids, dead bodies, fruit bats, and nonhuman primates. International travelers returning to the United States from these countries are advised to self-monitor for Marburg symptoms during travel and for 21 days after country departure. Travelers who develop signs or symptoms of MVD should immediately self-isolate and contact their local health department or clinician.

So, how should clinicians manage such return travelers? In the setting of these new MVD outbreaks in sub-Saharan Africa, what do U.S. clinicians need to know? Clinicians should consider MVD in the differential diagnosis of ill patients with a compatible exposure history and clinical presentation. A detailed exposure history should be obtained to determine if patients have been to an area with an active MVD outbreak during their incubation period (in the past 21 days), had concerning epidemiologic risk factors (for example, presence at funerals, health care facilities, in mines/caves) while in the affected area, and/or had contact with a suspected or confirmed MVD case.

Clinical diagnosis of MVD is challenging as the initial dry symptoms of infection are nonspecific (fever, influenza-like illness, malaise, anorexia, etc.) and can resemble other febrile infectious illnesses. Similarly, presenting alternative or concurrent infections, particularly in febrile return travelers, include malaria, Lassa fever, typhoid, and measles. From these nonspecific symptoms, patients with MVD can then progress to the more severe wet symptoms (for example, vomiting, diarrhea, and bleeding). Common clinical features of MVD have been described based on the clinical presentation and course of cases in MVD outbreaks. Notably, in the original Marburg outbreak, maculopapular rash and conjunctival injection were early patient symptoms and most patient deaths occurred during the second week of illness progression.

Supportive care, including aggressive fluid replacement, is the mainstay of therapy for MVD. Currently, there are no Food and Drug Administration–approved antiviral treatments or vaccines for Marburg virus. Despite their viral similarities, vaccines against Ebola virus have not been shown to be protective against Marburg virus. Marburg virus vaccine development is ongoing, with a few promising candidate vaccines in early phase 1 and 2 clinical trials. In 2022, in response to MVD outbreaks in Ghana and Guinea, the World Health Organization convened an international Marburg virus vaccine consortium which is working to promote global research collaboration for more rapid vaccine development.

In the absence of definitive therapies, early identification of patients with suspected MVD is critical for preventing the spread of infection to close contacts. Like Ebola virus–infected patients, only symptomatic MVD patients are infectious and all patients with suspected MVD should be isolated in a private room and cared for in accordance with infection control procedures. As MVD is a nationally notifiable disease, suspected cases should be reported to local or state health departments as per jurisdictional requirements. Clinicians should also consult with their local or state health department and CDC for guidance on testing patients with suspected MVD and consider prompt evaluation for other infectious etiologies in the patient’s differential diagnosis. Comprehensive guidance for clinicians on screening and diagnosing patients with MVD is available on the CDC website at https://www.cdc.gov/vhf/marburg/index.html.

Dr. Appiah (she/her) is a medical epidemiologist in the division of global migration and quarantine at the CDC. Dr. Appiah holds adjunct faculty appointment in the division of infectious diseases at Emory University, Atlanta. She also holds a commission in the U.S. Public Health Service and is a resident advisor, Uganda, U.S. President’s Malaria Initiative, at the CDC.

What do green monkeys, fruit bats, and python caves all have in common? All have been implicated in outbreaks as transmission sources of the rare but deadly Marburg virus. Marburg virus is in the same Filoviridae family of highly pathogenic RNA viruses as Ebola virus, and similarly can cause a rapidly progressive and fatal viral hemorrhagic fever.

In the first reported Marburg outbreak in 1967, laboratory workers in Marburg and Frankfurt, Germany, and in Belgrade, Yugoslavia, developed severe febrile illnesses with massive hemorrhage and multiorgan system dysfunction after contact with infected African green monkeys imported from Uganda. Since the first discovery of Marburg virus, there have been over 14 Marburg virus disease (MVD) outbreaks worldwide with nearly 600 cases and case fatality rates of 23%-90%.

The majority of MVD outbreaks have occurred in sub-Saharan Africa, and primarily in three African countries: Angola, the Democratic Republic of Congo, and Uganda. In sub-Saharan Africa, these sporadic outbreaks have had high case fatality rates (up to 80%-90%) and been linked to human exposure to the oral secretions or urinary/fecal droppings of Egyptian fruit bats (Rousettus aegyptiacus), the animal reservoir for Marburg virus. These exposures have primarily occurred among miners or tourists frequenting bat-infested mines or caves, including Uganda’s python cave, where Centers for Disease Control and Prevention investigators have conducted ecological studies on Marburg-infected bats. Person-to-person transmission occurs from direct contact with the blood or bodily fluids of an infected person or contact with a contaminated object (for example, unsterilized needles and syringes in a large nosocomial outbreak in Angola).

On April 6, 2023, the CDC issued a Health Advisory for U.S. clinicians and public health departments regarding two separate MVD outbreaks in Equatorial Guinea and Tanzania. These first-ever MVD outbreaks in both West and East African countries appear to be epidemiologically unrelated. As of March 24, 2023, in Equatorial Guinea, a total of 15 confirmed cases, including 11 deaths, and 23 probable cases, all deceased, have been identified in multiple districts since the outbreak declaration in February 2023. In Tanzania, a total of eight cases, including five deaths, have been reported among villagers in a northwest region since the outbreak declaration in March 2023. While so far cases in the Tanzania MVD outbreak have been epidemiologically linked, in Equatorial Guinea some cases have no identified epidemiological links, raising concern for ongoing community spread.

To date, no cases in these outbreaks have been reported in the United States or outside the affected countries. Overall, the risk of MVD in nonendemic countries, like the United States, is low but there is still a risk of importation. As of May 2, 2023, CDC has issued a Level 2 travel alert (practice enhanced precautions) for Marburg in Equatorial Guinea and a Level 1 travel watch (practice usual precautions) for Marburg in Tanzania. Travelers to these countries are advised to avoid nonessential travel to areas with active outbreaks and practice preventative measures, including avoiding contact with sick people, blood and bodily fluids, dead bodies, fruit bats, and nonhuman primates. International travelers returning to the United States from these countries are advised to self-monitor for Marburg symptoms during travel and for 21 days after country departure. Travelers who develop signs or symptoms of MVD should immediately self-isolate and contact their local health department or clinician.

So, how should clinicians manage such return travelers? In the setting of these new MVD outbreaks in sub-Saharan Africa, what do U.S. clinicians need to know? Clinicians should consider MVD in the differential diagnosis of ill patients with a compatible exposure history and clinical presentation. A detailed exposure history should be obtained to determine if patients have been to an area with an active MVD outbreak during their incubation period (in the past 21 days), had concerning epidemiologic risk factors (for example, presence at funerals, health care facilities, in mines/caves) while in the affected area, and/or had contact with a suspected or confirmed MVD case.

Clinical diagnosis of MVD is challenging as the initial dry symptoms of infection are nonspecific (fever, influenza-like illness, malaise, anorexia, etc.) and can resemble other febrile infectious illnesses. Similarly, presenting alternative or concurrent infections, particularly in febrile return travelers, include malaria, Lassa fever, typhoid, and measles. From these nonspecific symptoms, patients with MVD can then progress to the more severe wet symptoms (for example, vomiting, diarrhea, and bleeding). Common clinical features of MVD have been described based on the clinical presentation and course of cases in MVD outbreaks. Notably, in the original Marburg outbreak, maculopapular rash and conjunctival injection were early patient symptoms and most patient deaths occurred during the second week of illness progression.

Supportive care, including aggressive fluid replacement, is the mainstay of therapy for MVD. Currently, there are no Food and Drug Administration–approved antiviral treatments or vaccines for Marburg virus. Despite their viral similarities, vaccines against Ebola virus have not been shown to be protective against Marburg virus. Marburg virus vaccine development is ongoing, with a few promising candidate vaccines in early phase 1 and 2 clinical trials. In 2022, in response to MVD outbreaks in Ghana and Guinea, the World Health Organization convened an international Marburg virus vaccine consortium which is working to promote global research collaboration for more rapid vaccine development.

In the absence of definitive therapies, early identification of patients with suspected MVD is critical for preventing the spread of infection to close contacts. Like Ebola virus–infected patients, only symptomatic MVD patients are infectious and all patients with suspected MVD should be isolated in a private room and cared for in accordance with infection control procedures. As MVD is a nationally notifiable disease, suspected cases should be reported to local or state health departments as per jurisdictional requirements. Clinicians should also consult with their local or state health department and CDC for guidance on testing patients with suspected MVD and consider prompt evaluation for other infectious etiologies in the patient’s differential diagnosis. Comprehensive guidance for clinicians on screening and diagnosing patients with MVD is available on the CDC website at https://www.cdc.gov/vhf/marburg/index.html.

Dr. Appiah (she/her) is a medical epidemiologist in the division of global migration and quarantine at the CDC. Dr. Appiah holds adjunct faculty appointment in the division of infectious diseases at Emory University, Atlanta. She also holds a commission in the U.S. Public Health Service and is a resident advisor, Uganda, U.S. President’s Malaria Initiative, at the CDC.

What do green monkeys, fruit bats, and python caves all have in common? All have been implicated in outbreaks as transmission sources of the rare but deadly Marburg virus. Marburg virus is in the same Filoviridae family of highly pathogenic RNA viruses as Ebola virus, and similarly can cause a rapidly progressive and fatal viral hemorrhagic fever.

In the first reported Marburg outbreak in 1967, laboratory workers in Marburg and Frankfurt, Germany, and in Belgrade, Yugoslavia, developed severe febrile illnesses with massive hemorrhage and multiorgan system dysfunction after contact with infected African green monkeys imported from Uganda. Since the first discovery of Marburg virus, there have been over 14 Marburg virus disease (MVD) outbreaks worldwide with nearly 600 cases and case fatality rates of 23%-90%.

The majority of MVD outbreaks have occurred in sub-Saharan Africa, and primarily in three African countries: Angola, the Democratic Republic of Congo, and Uganda. In sub-Saharan Africa, these sporadic outbreaks have had high case fatality rates (up to 80%-90%) and been linked to human exposure to the oral secretions or urinary/fecal droppings of Egyptian fruit bats (Rousettus aegyptiacus), the animal reservoir for Marburg virus. These exposures have primarily occurred among miners or tourists frequenting bat-infested mines or caves, including Uganda’s python cave, where Centers for Disease Control and Prevention investigators have conducted ecological studies on Marburg-infected bats. Person-to-person transmission occurs from direct contact with the blood or bodily fluids of an infected person or contact with a contaminated object (for example, unsterilized needles and syringes in a large nosocomial outbreak in Angola).

On April 6, 2023, the CDC issued a Health Advisory for U.S. clinicians and public health departments regarding two separate MVD outbreaks in Equatorial Guinea and Tanzania. These first-ever MVD outbreaks in both West and East African countries appear to be epidemiologically unrelated. As of March 24, 2023, in Equatorial Guinea, a total of 15 confirmed cases, including 11 deaths, and 23 probable cases, all deceased, have been identified in multiple districts since the outbreak declaration in February 2023. In Tanzania, a total of eight cases, including five deaths, have been reported among villagers in a northwest region since the outbreak declaration in March 2023. While so far cases in the Tanzania MVD outbreak have been epidemiologically linked, in Equatorial Guinea some cases have no identified epidemiological links, raising concern for ongoing community spread.

To date, no cases in these outbreaks have been reported in the United States or outside the affected countries. Overall, the risk of MVD in nonendemic countries, like the United States, is low but there is still a risk of importation. As of May 2, 2023, CDC has issued a Level 2 travel alert (practice enhanced precautions) for Marburg in Equatorial Guinea and a Level 1 travel watch (practice usual precautions) for Marburg in Tanzania. Travelers to these countries are advised to avoid nonessential travel to areas with active outbreaks and practice preventative measures, including avoiding contact with sick people, blood and bodily fluids, dead bodies, fruit bats, and nonhuman primates. International travelers returning to the United States from these countries are advised to self-monitor for Marburg symptoms during travel and for 21 days after country departure. Travelers who develop signs or symptoms of MVD should immediately self-isolate and contact their local health department or clinician.

So, how should clinicians manage such return travelers? In the setting of these new MVD outbreaks in sub-Saharan Africa, what do U.S. clinicians need to know? Clinicians should consider MVD in the differential diagnosis of ill patients with a compatible exposure history and clinical presentation. A detailed exposure history should be obtained to determine if patients have been to an area with an active MVD outbreak during their incubation period (in the past 21 days), had concerning epidemiologic risk factors (for example, presence at funerals, health care facilities, in mines/caves) while in the affected area, and/or had contact with a suspected or confirmed MVD case.

Clinical diagnosis of MVD is challenging as the initial dry symptoms of infection are nonspecific (fever, influenza-like illness, malaise, anorexia, etc.) and can resemble other febrile infectious illnesses. Similarly, presenting alternative or concurrent infections, particularly in febrile return travelers, include malaria, Lassa fever, typhoid, and measles. From these nonspecific symptoms, patients with MVD can then progress to the more severe wet symptoms (for example, vomiting, diarrhea, and bleeding). Common clinical features of MVD have been described based on the clinical presentation and course of cases in MVD outbreaks. Notably, in the original Marburg outbreak, maculopapular rash and conjunctival injection were early patient symptoms and most patient deaths occurred during the second week of illness progression.

Supportive care, including aggressive fluid replacement, is the mainstay of therapy for MVD. Currently, there are no Food and Drug Administration–approved antiviral treatments or vaccines for Marburg virus. Despite their viral similarities, vaccines against Ebola virus have not been shown to be protective against Marburg virus. Marburg virus vaccine development is ongoing, with a few promising candidate vaccines in early phase 1 and 2 clinical trials. In 2022, in response to MVD outbreaks in Ghana and Guinea, the World Health Organization convened an international Marburg virus vaccine consortium which is working to promote global research collaboration for more rapid vaccine development.

In the absence of definitive therapies, early identification of patients with suspected MVD is critical for preventing the spread of infection to close contacts. Like Ebola virus–infected patients, only symptomatic MVD patients are infectious and all patients with suspected MVD should be isolated in a private room and cared for in accordance with infection control procedures. As MVD is a nationally notifiable disease, suspected cases should be reported to local or state health departments as per jurisdictional requirements. Clinicians should also consult with their local or state health department and CDC for guidance on testing patients with suspected MVD and consider prompt evaluation for other infectious etiologies in the patient’s differential diagnosis. Comprehensive guidance for clinicians on screening and diagnosing patients with MVD is available on the CDC website at https://www.cdc.gov/vhf/marburg/index.html.

Dr. Appiah (she/her) is a medical epidemiologist in the division of global migration and quarantine at the CDC. Dr. Appiah holds adjunct faculty appointment in the division of infectious diseases at Emory University, Atlanta. She also holds a commission in the U.S. Public Health Service and is a resident advisor, Uganda, U.S. President’s Malaria Initiative, at the CDC.

The U.S. government plans to no longer require federal workers or international air travelers to be vaccinated for COVID-19, the Biden administration has announced. 

The move means vaccines will no longer be required for workers who are federal employees, federal contractors, Head Start early education employees, workers at Medicare-certified health care facilities, and those who work at U.S. borders. International air travelers will no longer be required to prove their vaccination status. The requirement will be lifted at the end of the day on May 11, which is also when the federal public health emergency declaration ends.

“While vaccination remains one of the most important tools in advancing the health and safety of employees and promoting the efficiency of workplaces, we are now in a different phase of our response when these measures are no longer necessary,” an announcement from the White House stated.

White House officials credited vaccine requirements with saving millions of lives, noting that the rules ensured “the safety of workers in critical workforces including those in the healthcare and education sectors, protecting themselves and the populations they serve, and strengthening their ability to provide services without disruptions to operations.”

More than 100 million people were subject to the vaccine requirement, The Associated Press reported. All but 2% of those covered by the mandate had received at least one dose or had a pending or approved exception on file by January 2022, the Biden administration said, noting that COVID deaths have dropped 95% since January 2021 and hospitalizations are down nearly 91%.

In January, vaccine requirements were lifted for U.S. military members.

On the government-run website Safer Federal Workforce, which helped affected organizations put federal COVID rules into place, agencies were told to “take no action to implement or enforce the COVID-19 vaccination requirement” at this time.

A version of this article first appeared on WebMD.com.

The U.S. government plans to no longer require federal workers or international air travelers to be vaccinated for COVID-19, the Biden administration has announced. 

The move means vaccines will no longer be required for workers who are federal employees, federal contractors, Head Start early education employees, workers at Medicare-certified health care facilities, and those who work at U.S. borders. International air travelers will no longer be required to prove their vaccination status. The requirement will be lifted at the end of the day on May 11, which is also when the federal public health emergency declaration ends.

“While vaccination remains one of the most important tools in advancing the health and safety of employees and promoting the efficiency of workplaces, we are now in a different phase of our response when these measures are no longer necessary,” an announcement from the White House stated.

White House officials credited vaccine requirements with saving millions of lives, noting that the rules ensured “the safety of workers in critical workforces including those in the healthcare and education sectors, protecting themselves and the populations they serve, and strengthening their ability to provide services without disruptions to operations.”

More than 100 million people were subject to the vaccine requirement, The Associated Press reported. All but 2% of those covered by the mandate had received at least one dose or had a pending or approved exception on file by January 2022, the Biden administration said, noting that COVID deaths have dropped 95% since January 2021 and hospitalizations are down nearly 91%.

In January, vaccine requirements were lifted for U.S. military members.

On the government-run website Safer Federal Workforce, which helped affected organizations put federal COVID rules into place, agencies were told to “take no action to implement or enforce the COVID-19 vaccination requirement” at this time.

A version of this article first appeared on WebMD.com.

The U.S. government plans to no longer require federal workers or international air travelers to be vaccinated for COVID-19, the Biden administration has announced. 

The move means vaccines will no longer be required for workers who are federal employees, federal contractors, Head Start early education employees, workers at Medicare-certified health care facilities, and those who work at U.S. borders. International air travelers will no longer be required to prove their vaccination status. The requirement will be lifted at the end of the day on May 11, which is also when the federal public health emergency declaration ends.

“While vaccination remains one of the most important tools in advancing the health and safety of employees and promoting the efficiency of workplaces, we are now in a different phase of our response when these measures are no longer necessary,” an announcement from the White House stated.

White House officials credited vaccine requirements with saving millions of lives, noting that the rules ensured “the safety of workers in critical workforces including those in the healthcare and education sectors, protecting themselves and the populations they serve, and strengthening their ability to provide services without disruptions to operations.”

More than 100 million people were subject to the vaccine requirement, The Associated Press reported. All but 2% of those covered by the mandate had received at least one dose or had a pending or approved exception on file by January 2022, the Biden administration said, noting that COVID deaths have dropped 95% since January 2021 and hospitalizations are down nearly 91%.

In January, vaccine requirements were lifted for U.S. military members.

On the government-run website Safer Federal Workforce, which helped affected organizations put federal COVID rules into place, agencies were told to “take no action to implement or enforce the COVID-19 vaccination requirement” at this time.

A version of this article first appeared on WebMD.com.

WASHINGTON – Approximately 70% of children with febrile urinary tract infections receive guideline-adherent follow-up imaging from primary care, based on data from 118 individuals.

“Timely imaging is recommended after febrile UTI (fUTI) in young children to identify treatable urologic conditions,” wrote Jonathan Hatoun, MD, of Boston Children’s Hospital, and colleagues in a poster presented at the Pediatric Academic Societies annual meeting.

The American Academy of Pediatrics (AAP) currently recommends renal-bladder ultrasound (RBUS) after fUTI with voiding cystourethrogram (VCUG) after abnormal RBUS or second fUTI, but data on clinician adherence to these recommendations are limited, the researchers said.

To characterize practice patterns regarding fUTI, the researchers reviewed data from children younger than 24 months of age with fUTI who were treated at a primary care network in Massachusetts in 2019. The definition of fUTI was temperature of 38° C or higher, positive urinalysis, and more than 50,000 CFU on urine culture. The median age of the patients was 9 months; 84% were female.

In a multivariate analysis, post-UTI imaging followed the AAP guidelines in 82 cases (69.5%). The main reasons for nonadherence were lack of RBUS in 21 patients, VCUG despite normal RBUS in 9 patients, no VCUG after abnormal RBUS in 4 patients, and no VCUG after a second fUTI in 2 patients.

Overall, nonadherence was a result of not ordering a recommended study in 23% of cases (errors of omission) and ordering an unnecessary study in 8% of cases (errors of commission).

Commercial insurance, larger number of providers in practice, and younger provider age were significant independent predictors of adherence (odds ratios 2.82, 1.38, and 0.96, respectively).

The findings were limited by the use of data from a single center; however, the results suggest that targeted training may improve guideline adherence, the researchers wrote. Additional research and quality improvement studies are needed to understand and address the impact of insurance on guideline adherence for imaging after febrile UTIs, they noted.
 

Provider education is essential to continued quality of care

When it comes to febrile UTIs, “it is important to stay focused on the quality of care being provided, as opposed to the usual benchmark of quantity of care,” Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“This is a very simple but interesting study on provider compliance with practice guidelines,” said Dr. Joos, who was not involved in the study. “I was surprised that the providers did so well in ordering the correct imaging in 70% of the cases,” he said.

 Of particular interest, Dr. Joos noted, was that “the authors also showed that older providers and those working in smaller practices are less likely to comply with this particular imaging guideline. This can be summed up as the ‘I didn’t know the guideline’ effect.”

To improve quality of care, “more research and effort should be directed at updating providers when strong new evidence changes previous practices and guidelines,” Dr. Joos told this news organization.

The study received no outside funding. The researchers and Dr. Joos had no financial conflicts to disclose.

WASHINGTON – Approximately 70% of children with febrile urinary tract infections receive guideline-adherent follow-up imaging from primary care, based on data from 118 individuals.

“Timely imaging is recommended after febrile UTI (fUTI) in young children to identify treatable urologic conditions,” wrote Jonathan Hatoun, MD, of Boston Children’s Hospital, and colleagues in a poster presented at the Pediatric Academic Societies annual meeting.

The American Academy of Pediatrics (AAP) currently recommends renal-bladder ultrasound (RBUS) after fUTI with voiding cystourethrogram (VCUG) after abnormal RBUS or second fUTI, but data on clinician adherence to these recommendations are limited, the researchers said.

To characterize practice patterns regarding fUTI, the researchers reviewed data from children younger than 24 months of age with fUTI who were treated at a primary care network in Massachusetts in 2019. The definition of fUTI was temperature of 38° C or higher, positive urinalysis, and more than 50,000 CFU on urine culture. The median age of the patients was 9 months; 84% were female.

In a multivariate analysis, post-UTI imaging followed the AAP guidelines in 82 cases (69.5%). The main reasons for nonadherence were lack of RBUS in 21 patients, VCUG despite normal RBUS in 9 patients, no VCUG after abnormal RBUS in 4 patients, and no VCUG after a second fUTI in 2 patients.

Overall, nonadherence was a result of not ordering a recommended study in 23% of cases (errors of omission) and ordering an unnecessary study in 8% of cases (errors of commission).

Commercial insurance, larger number of providers in practice, and younger provider age were significant independent predictors of adherence (odds ratios 2.82, 1.38, and 0.96, respectively).

The findings were limited by the use of data from a single center; however, the results suggest that targeted training may improve guideline adherence, the researchers wrote. Additional research and quality improvement studies are needed to understand and address the impact of insurance on guideline adherence for imaging after febrile UTIs, they noted.
 

Provider education is essential to continued quality of care

When it comes to febrile UTIs, “it is important to stay focused on the quality of care being provided, as opposed to the usual benchmark of quantity of care,” Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“This is a very simple but interesting study on provider compliance with practice guidelines,” said Dr. Joos, who was not involved in the study. “I was surprised that the providers did so well in ordering the correct imaging in 70% of the cases,” he said.

 Of particular interest, Dr. Joos noted, was that “the authors also showed that older providers and those working in smaller practices are less likely to comply with this particular imaging guideline. This can be summed up as the ‘I didn’t know the guideline’ effect.”

To improve quality of care, “more research and effort should be directed at updating providers when strong new evidence changes previous practices and guidelines,” Dr. Joos told this news organization.

The study received no outside funding. The researchers and Dr. Joos had no financial conflicts to disclose.

WASHINGTON – Approximately 70% of children with febrile urinary tract infections receive guideline-adherent follow-up imaging from primary care, based on data from 118 individuals.

“Timely imaging is recommended after febrile UTI (fUTI) in young children to identify treatable urologic conditions,” wrote Jonathan Hatoun, MD, of Boston Children’s Hospital, and colleagues in a poster presented at the Pediatric Academic Societies annual meeting.

The American Academy of Pediatrics (AAP) currently recommends renal-bladder ultrasound (RBUS) after fUTI with voiding cystourethrogram (VCUG) after abnormal RBUS or second fUTI, but data on clinician adherence to these recommendations are limited, the researchers said.

To characterize practice patterns regarding fUTI, the researchers reviewed data from children younger than 24 months of age with fUTI who were treated at a primary care network in Massachusetts in 2019. The definition of fUTI was temperature of 38° C or higher, positive urinalysis, and more than 50,000 CFU on urine culture. The median age of the patients was 9 months; 84% were female.

In a multivariate analysis, post-UTI imaging followed the AAP guidelines in 82 cases (69.5%). The main reasons for nonadherence were lack of RBUS in 21 patients, VCUG despite normal RBUS in 9 patients, no VCUG after abnormal RBUS in 4 patients, and no VCUG after a second fUTI in 2 patients.

Overall, nonadherence was a result of not ordering a recommended study in 23% of cases (errors of omission) and ordering an unnecessary study in 8% of cases (errors of commission).

Commercial insurance, larger number of providers in practice, and younger provider age were significant independent predictors of adherence (odds ratios 2.82, 1.38, and 0.96, respectively).

The findings were limited by the use of data from a single center; however, the results suggest that targeted training may improve guideline adherence, the researchers wrote. Additional research and quality improvement studies are needed to understand and address the impact of insurance on guideline adherence for imaging after febrile UTIs, they noted.
 

Provider education is essential to continued quality of care

When it comes to febrile UTIs, “it is important to stay focused on the quality of care being provided, as opposed to the usual benchmark of quantity of care,” Tim Joos, MD, a Seattle-based clinician with a combination internal medicine/pediatrics practice, said in an interview.

“This is a very simple but interesting study on provider compliance with practice guidelines,” said Dr. Joos, who was not involved in the study. “I was surprised that the providers did so well in ordering the correct imaging in 70% of the cases,” he said.

 Of particular interest, Dr. Joos noted, was that “the authors also showed that older providers and those working in smaller practices are less likely to comply with this particular imaging guideline. This can be summed up as the ‘I didn’t know the guideline’ effect.”

To improve quality of care, “more research and effort should be directed at updating providers when strong new evidence changes previous practices and guidelines,” Dr. Joos told this news organization.

The study received no outside funding. The researchers and Dr. Joos had no financial conflicts to disclose.

The recent approval of the first oral fecal-derived microbiota therapy to prevent the recurrence of Clostridioides difficile (C. diff) infection in patients was welcome news for physicians who’ve struggled under the weight of having too few treatment options for the prevention of C. diff recurrence.

The product, developed by Massachusetts-based Seres Therepeutics and marketed as Vowst, was approved by the U.S. Food and Drug Administration on April 26. It is approved for use in adults who have already been treated with antibiotics for a recurrent infection with C. diff bacteria.

This is the first oral treatment for the prevention of C. diff recurrence and is designed to be delivered in four capsules taken daily for 3 days.

Gastroenterologist Phillip I. Tarr, MD, division chief of gastroenterology at Washington University, St. Louis, and chair of the American Gastroenterological Association Center for Gut Microbiome Research and Education, said that prevention of recurrent C. diff infection “remains challenging,” and that Vowst “provides the first FDA-approved, orally administered microbiome therapeutic with which to achieve this goal. This advance also makes us optimistic we might soon be able to prevent other disorders by managing gut microbial communities.”

Vowst is the second therapy derived from human stool to be approved for the indication in less than 6 months. In December, the FDA approved Rebyota (Ferring), a rectally delivered treatment that also uses microbes from donor feces. Both products were given priority review, orphan drug, and breakthrough therapy designations by the agency.

C. diff infection can be aggravated by an alteration of normal gut flora associated with antibiotics treatment, leading to cycles of repeated infections. Infection can produce diarrhea, abdominal pain, fever, and severe morbidity. In the United States, an estimated 15,000 to 30,000 deaths per year are linked to C. diff. Risk factors for recurrent infection include being 65 or older, hospitalization, being in a nursing home, a weakened immune system, and previous infection with C. diff.

Therapies transplanting fecal microbiota from donors have been used since the 1950s as treatments for recurrent C. diff infection, and in the past decade, as stool banks recruiting screened donors have made fecal microbiota transplants, or FMT, standard of care. However, only in recent years have fecal-derived therapies become subject to standardized safety and efficacy testing.

Both the current FDA-approved products, Rebyota and Vowst, were shown in randomized controlled trials to reduce recurrence of C. diff infection, compared with placebo. In a phase 3 clinical trial of Rebyota (n = 262) in antibiotic-treated patients, one rectally administered dose reduced recurrence of C. diff infection by 70.6% at 8 weeks, compared with 57.5% for placebo. A phase 3 study of Vowst (n = 281) showed recurrence in treated subjects to be 12.4% at 8 weeks, compared with nearly 40% of those receiving placebo (relative risk, 0.32; 95% confidence interval, 0.18-0.58; P less than .001).

Despite screening protocols that have become increasingly homogenized and rigorous, FMT is associated with the risk of introducing pathogens. Vowst is manufactured with purified bacterial spores derived from donor feces, not whole stool. Nonetheless, FDA noted in its statement that Vowst could still potentially introduce infectious agents or allergens.
 

Antibiotics are still first-line treatment

In an interview, Jessica Allegretti, MD, MPH, AGAF, medical director of the Crohn’s and Colitis Center at Brigham & Women’s Hospital, Boston, said that having two FDA-approved therapies with different means of administration “is great for the field and great for patients. These are both meant to be used after a course of antibiotics, so antibiotics are still the mainstay of treatment for C. diff and recurrent C. diff, but we now have more options to prevent recurrence.”

The convenience of an oral therapy that can be taken at home is “very attractive,” Dr. Allegretti added, noting that there will also be patients “who either don’t want to or can’t take capsules, for whom a rectal administration [in a health care setting] may be preferred.”

Dr. Allegretti, who has used FMT to treat recurrent C. difficile for more than a decade, said that she expected traditional FMT using screened donor stool to remain available even as the new products are adopted by clinicians. FMT centers like OpenBiome “will continue to provide access for patients who either don’t have the ability to get the FDA-approved products because of insurance coverage, or for financial reasons, or maybe neither of the new products is appropriate for them,” she said. “I do think there will always be a need for the traditional option. The more options that we have available the better.”

TD Cowen analyst Joseph Thome told Reuters that the drug could be priced close to $20,000 per course, expecting peak sales of $750 million in the U.S. in 2033.

Dr. Allegretti disclosed consulting work for Seres Therapeutics, Ferring, and other manufacturers. She is a member of OpenBiome’s clinical advisory board.

The recent approval of the first oral fecal-derived microbiota therapy to prevent the recurrence of Clostridioides difficile (C. diff) infection in patients was welcome news for physicians who’ve struggled under the weight of having too few treatment options for the prevention of C. diff recurrence.

The product, developed by Massachusetts-based Seres Therepeutics and marketed as Vowst, was approved by the U.S. Food and Drug Administration on April 26. It is approved for use in adults who have already been treated with antibiotics for a recurrent infection with C. diff bacteria.

This is the first oral treatment for the prevention of C. diff recurrence and is designed to be delivered in four capsules taken daily for 3 days.

Gastroenterologist Phillip I. Tarr, MD, division chief of gastroenterology at Washington University, St. Louis, and chair of the American Gastroenterological Association Center for Gut Microbiome Research and Education, said that prevention of recurrent C. diff infection “remains challenging,” and that Vowst “provides the first FDA-approved, orally administered microbiome therapeutic with which to achieve this goal. This advance also makes us optimistic we might soon be able to prevent other disorders by managing gut microbial communities.”

Vowst is the second therapy derived from human stool to be approved for the indication in less than 6 months. In December, the FDA approved Rebyota (Ferring), a rectally delivered treatment that also uses microbes from donor feces. Both products were given priority review, orphan drug, and breakthrough therapy designations by the agency.

C. diff infection can be aggravated by an alteration of normal gut flora associated with antibiotics treatment, leading to cycles of repeated infections. Infection can produce diarrhea, abdominal pain, fever, and severe morbidity. In the United States, an estimated 15,000 to 30,000 deaths per year are linked to C. diff. Risk factors for recurrent infection include being 65 or older, hospitalization, being in a nursing home, a weakened immune system, and previous infection with C. diff.

Therapies transplanting fecal microbiota from donors have been used since the 1950s as treatments for recurrent C. diff infection, and in the past decade, as stool banks recruiting screened donors have made fecal microbiota transplants, or FMT, standard of care. However, only in recent years have fecal-derived therapies become subject to standardized safety and efficacy testing.

Both the current FDA-approved products, Rebyota and Vowst, were shown in randomized controlled trials to reduce recurrence of C. diff infection, compared with placebo. In a phase 3 clinical trial of Rebyota (n = 262) in antibiotic-treated patients, one rectally administered dose reduced recurrence of C. diff infection by 70.6% at 8 weeks, compared with 57.5% for placebo. A phase 3 study of Vowst (n = 281) showed recurrence in treated subjects to be 12.4% at 8 weeks, compared with nearly 40% of those receiving placebo (relative risk, 0.32; 95% confidence interval, 0.18-0.58; P less than .001).

Despite screening protocols that have become increasingly homogenized and rigorous, FMT is associated with the risk of introducing pathogens. Vowst is manufactured with purified bacterial spores derived from donor feces, not whole stool. Nonetheless, FDA noted in its statement that Vowst could still potentially introduce infectious agents or allergens.
 

Antibiotics are still first-line treatment

In an interview, Jessica Allegretti, MD, MPH, AGAF, medical director of the Crohn’s and Colitis Center at Brigham & Women’s Hospital, Boston, said that having two FDA-approved therapies with different means of administration “is great for the field and great for patients. These are both meant to be used after a course of antibiotics, so antibiotics are still the mainstay of treatment for C. diff and recurrent C. diff, but we now have more options to prevent recurrence.”

The convenience of an oral therapy that can be taken at home is “very attractive,” Dr. Allegretti added, noting that there will also be patients “who either don’t want to or can’t take capsules, for whom a rectal administration [in a health care setting] may be preferred.”

Dr. Allegretti, who has used FMT to treat recurrent C. difficile for more than a decade, said that she expected traditional FMT using screened donor stool to remain available even as the new products are adopted by clinicians. FMT centers like OpenBiome “will continue to provide access for patients who either don’t have the ability to get the FDA-approved products because of insurance coverage, or for financial reasons, or maybe neither of the new products is appropriate for them,” she said. “I do think there will always be a need for the traditional option. The more options that we have available the better.”

TD Cowen analyst Joseph Thome told Reuters that the drug could be priced close to $20,000 per course, expecting peak sales of $750 million in the U.S. in 2033.

Dr. Allegretti disclosed consulting work for Seres Therapeutics, Ferring, and other manufacturers. She is a member of OpenBiome’s clinical advisory board.

The recent approval of the first oral fecal-derived microbiota therapy to prevent the recurrence of Clostridioides difficile (C. diff) infection in patients was welcome news for physicians who’ve struggled under the weight of having too few treatment options for the prevention of C. diff recurrence.

The product, developed by Massachusetts-based Seres Therepeutics and marketed as Vowst, was approved by the U.S. Food and Drug Administration on April 26. It is approved for use in adults who have already been treated with antibiotics for a recurrent infection with C. diff bacteria.

This is the first oral treatment for the prevention of C. diff recurrence and is designed to be delivered in four capsules taken daily for 3 days.

Gastroenterologist Phillip I. Tarr, MD, division chief of gastroenterology at Washington University, St. Louis, and chair of the American Gastroenterological Association Center for Gut Microbiome Research and Education, said that prevention of recurrent C. diff infection “remains challenging,” and that Vowst “provides the first FDA-approved, orally administered microbiome therapeutic with which to achieve this goal. This advance also makes us optimistic we might soon be able to prevent other disorders by managing gut microbial communities.”

Vowst is the second therapy derived from human stool to be approved for the indication in less than 6 months. In December, the FDA approved Rebyota (Ferring), a rectally delivered treatment that also uses microbes from donor feces. Both products were given priority review, orphan drug, and breakthrough therapy designations by the agency.

C. diff infection can be aggravated by an alteration of normal gut flora associated with antibiotics treatment, leading to cycles of repeated infections. Infection can produce diarrhea, abdominal pain, fever, and severe morbidity. In the United States, an estimated 15,000 to 30,000 deaths per year are linked to C. diff. Risk factors for recurrent infection include being 65 or older, hospitalization, being in a nursing home, a weakened immune system, and previous infection with C. diff.

Therapies transplanting fecal microbiota from donors have been used since the 1950s as treatments for recurrent C. diff infection, and in the past decade, as stool banks recruiting screened donors have made fecal microbiota transplants, or FMT, standard of care. However, only in recent years have fecal-derived therapies become subject to standardized safety and efficacy testing.

Both the current FDA-approved products, Rebyota and Vowst, were shown in randomized controlled trials to reduce recurrence of C. diff infection, compared with placebo. In a phase 3 clinical trial of Rebyota (n = 262) in antibiotic-treated patients, one rectally administered dose reduced recurrence of C. diff infection by 70.6% at 8 weeks, compared with 57.5% for placebo. A phase 3 study of Vowst (n = 281) showed recurrence in treated subjects to be 12.4% at 8 weeks, compared with nearly 40% of those receiving placebo (relative risk, 0.32; 95% confidence interval, 0.18-0.58; P less than .001).

Despite screening protocols that have become increasingly homogenized and rigorous, FMT is associated with the risk of introducing pathogens. Vowst is manufactured with purified bacterial spores derived from donor feces, not whole stool. Nonetheless, FDA noted in its statement that Vowst could still potentially introduce infectious agents or allergens.
 

Antibiotics are still first-line treatment

In an interview, Jessica Allegretti, MD, MPH, AGAF, medical director of the Crohn’s and Colitis Center at Brigham & Women’s Hospital, Boston, said that having two FDA-approved therapies with different means of administration “is great for the field and great for patients. These are both meant to be used after a course of antibiotics, so antibiotics are still the mainstay of treatment for C. diff and recurrent C. diff, but we now have more options to prevent recurrence.”

The convenience of an oral therapy that can be taken at home is “very attractive,” Dr. Allegretti added, noting that there will also be patients “who either don’t want to or can’t take capsules, for whom a rectal administration [in a health care setting] may be preferred.”

Dr. Allegretti, who has used FMT to treat recurrent C. difficile for more than a decade, said that she expected traditional FMT using screened donor stool to remain available even as the new products are adopted by clinicians. FMT centers like OpenBiome “will continue to provide access for patients who either don’t have the ability to get the FDA-approved products because of insurance coverage, or for financial reasons, or maybe neither of the new products is appropriate for them,” she said. “I do think there will always be a need for the traditional option. The more options that we have available the better.”

TD Cowen analyst Joseph Thome told Reuters that the drug could be priced close to $20,000 per course, expecting peak sales of $750 million in the U.S. in 2033.

Dr. Allegretti disclosed consulting work for Seres Therapeutics, Ferring, and other manufacturers. She is a member of OpenBiome’s clinical advisory board.

In September 2021, a community in Virginia experienced an outbreak of hepatitis A virus (HAV) that was ultimately linked to an infected food handler.¹ A total of 149 cases were reported over the next 12 months; 51 were directly related to the food handler and the remainder were the result of sustained community transmission. Of the 51 people who were directly infected by the food handler, 31 were hospitalized and 3 died. This incident offers important reminders about public health surveillance and the role that family physicians can play.

Hepatitis A virus is transmitted through food and drinks that have been contaminated by small amounts of stool that contains the virus or through close contact (including sexual contact) with a person who is infected. The incubation period can range from 15 to 59 days.

HAV generally resolves in a few days to weeks, with no long-term effects. However, recent outbreaks have been associated with high hospitalization and mortality rates because of the underlying comorbidities of those infected.

An increase in incidence. The national rate of HAV infection reached a low of less than 1/100,000 in 2015 but has since increased to almost 6/100,000 in 2019. This increase is mostly due to outbreaks linked to spread among people without a fixed residence, those who use illicit drugs, and men who have sex with men.²

In the Virginia outbreak, the food handler had a risk factor for HAV and was unvaccinated. He worked at 3 different locations of a restaurant chain for a total of 16 days while infectious, preparing ready-to-eat food without using gloves. Furthermore, he delayed seeking medical care for more than 2 weeks—at which time, the nature of his employment was not disclosed.

Prevention is straightforward. HAV infection can be prevented by administration of either HAV vaccine or immune globulin within 2 weeks of exposure.³ During an HAV outbreak, vaccination is recommended for people considered to be at risk, including those without a fixed residence, those who use illicit drugs, those who travel internationally, and men who have sex with men.³

There are 3 HAV vaccines available in the United States: 2 single-antigen vaccines, Havrix and Vaqta, both approved for children and adults, and a combination vaccine (containing both HAV and hepatitis B antigens), Twinrix, which is approved for those ages 18 years and older. All are inactivated vaccines.

What you can do. The Virginia outbreak illustrates the important role that family physicians can and do play in public health. We should:

• Encourage adults with risk factors for HAV to be vaccinated.
• Ask those with an HAV diagnosis about the people they may have exposed through personal contact or occupational exposure.
• Promptly report infectious diseases that are designated “reportable” to the public health department.
• Immediately report (by telephone) when HAV and other enteric infections involve a food handler.

In September 2021, a community in Virginia experienced an outbreak of hepatitis A virus (HAV) that was ultimately linked to an infected food handler.¹ A total of 149 cases were reported over the next 12 months; 51 were directly related to the food handler and the remainder were the result of sustained community transmission. Of the 51 people who were directly infected by the food handler, 31 were hospitalized and 3 died. This incident offers important reminders about public health surveillance and the role that family physicians can play.

Hepatitis A virus is transmitted through food and drinks that have been contaminated by small amounts of stool that contains the virus or through close contact (including sexual contact) with a person who is infected. The incubation period can range from 15 to 59 days.

HAV generally resolves in a few days to weeks, with no long-term effects. However, recent outbreaks have been associated with high hospitalization and mortality rates because of the underlying comorbidities of those infected.

An increase in incidence. The national rate of HAV infection reached a low of less than 1/100,000 in 2015 but has since increased to almost 6/100,000 in 2019. This increase is mostly due to outbreaks linked to spread among people without a fixed residence, those who use illicit drugs, and men who have sex with men.²

In the Virginia outbreak, the food handler had a risk factor for HAV and was unvaccinated. He worked at 3 different locations of a restaurant chain for a total of 16 days while infectious, preparing ready-to-eat food without using gloves. Furthermore, he delayed seeking medical care for more than 2 weeks—at which time, the nature of his employment was not disclosed.

Prevention is straightforward. HAV infection can be prevented by administration of either HAV vaccine or immune globulin within 2 weeks of exposure.³ During an HAV outbreak, vaccination is recommended for people considered to be at risk, including those without a fixed residence, those who use illicit drugs, those who travel internationally, and men who have sex with men.³

There are 3 HAV vaccines available in the United States: 2 single-antigen vaccines, Havrix and Vaqta, both approved for children and adults, and a combination vaccine (containing both HAV and hepatitis B antigens), Twinrix, which is approved for those ages 18 years and older. All are inactivated vaccines.

What you can do. The Virginia outbreak illustrates the important role that family physicians can and do play in public health. We should:

• Encourage adults with risk factors for HAV to be vaccinated.
• Ask those with an HAV diagnosis about the people they may have exposed through personal contact or occupational exposure.
• Promptly report infectious diseases that are designated “reportable” to the public health department.
• Immediately report (by telephone) when HAV and other enteric infections involve a food handler.

In September 2021, a community in Virginia experienced an outbreak of hepatitis A virus (HAV) that was ultimately linked to an infected food handler.¹ A total of 149 cases were reported over the next 12 months; 51 were directly related to the food handler and the remainder were the result of sustained community transmission. Of the 51 people who were directly infected by the food handler, 31 were hospitalized and 3 died. This incident offers important reminders about public health surveillance and the role that family physicians can play.

Hepatitis A virus is transmitted through food and drinks that have been contaminated by small amounts of stool that contains the virus or through close contact (including sexual contact) with a person who is infected. The incubation period can range from 15 to 59 days.

HAV generally resolves in a few days to weeks, with no long-term effects. However, recent outbreaks have been associated with high hospitalization and mortality rates because of the underlying comorbidities of those infected.

An increase in incidence. The national rate of HAV infection reached a low of less than 1/100,000 in 2015 but has since increased to almost 6/100,000 in 2019. This increase is mostly due to outbreaks linked to spread among people without a fixed residence, those who use illicit drugs, and men who have sex with men.²

In the Virginia outbreak, the food handler had a risk factor for HAV and was unvaccinated. He worked at 3 different locations of a restaurant chain for a total of 16 days while infectious, preparing ready-to-eat food without using gloves. Furthermore, he delayed seeking medical care for more than 2 weeks—at which time, the nature of his employment was not disclosed.

Prevention is straightforward. HAV infection can be prevented by administration of either HAV vaccine or immune globulin within 2 weeks of exposure.³ During an HAV outbreak, vaccination is recommended for people considered to be at risk, including those without a fixed residence, those who use illicit drugs, those who travel internationally, and men who have sex with men.³

There are 3 HAV vaccines available in the United States: 2 single-antigen vaccines, Havrix and Vaqta, both approved for children and adults, and a combination vaccine (containing both HAV and hepatitis B antigens), Twinrix, which is approved for those ages 18 years and older. All are inactivated vaccines.

What you can do. The Virginia outbreak illustrates the important role that family physicians can and do play in public health. We should:

• Encourage adults with risk factors for HAV to be vaccinated.
• Ask those with an HAV diagnosis about the people they may have exposed through personal contact or occupational exposure.
• Promptly report infectious diseases that are designated “reportable” to the public health department.
• Immediately report (by telephone) when HAV and other enteric infections involve a food handler.

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

Scent-detecting dogs have long been used to sniff out medical conditions ranging from low blood sugar and cancer to malaria, impending seizures, and migraines – not to mention explosives and narcotics.

Recently, the sensitivity of the canine nose has been tested as a strategy for screening for SARS-CoV-2 infection in schoolchildren showing no outward symptoms of the virus. A pilot study led by Carol A. Glaser, DVM, MD, of the California Department of Public Health in Richmond, found that trained dogs had an accuracy of more than 95% for detecting the odor of volatile organic compounds, or VOCs, produced by COVID-infected individuals.

California Department of Public Health

The authors believe that odor-based diagnosis with dogs could eventually provide a rapid, inexpensive, and noninvasive way to screen large groups for COVID-19 without the need for antigen testing.

“This is a new program with research ongoing, so it would be premature to consider it from a consumer’s perspective,” Dr. Glaser said in an interview. “However, the data look promising and we are hopeful we can continue to pilot various programs in various settings to see where, and if, dogs can be used for biomedical detection.”
 

In the lab and in the field

In a study published online in JAMA Pediatrics, Dr. Glaser’s group found that after 2 months’ training on COVID-19 scent samples in the laboratory, the dogs detected the presence of the virus more than 95% of the time. Antigen tests were used as a comparative reference.

In medical terms, the dogs achieved a greater than 95% accuracy on two important measures of effectiveness: sensitivity – a test’s ability to correctly detect the positive presence of disease – and specificity – the ability of a test to accurately rule out the presence of disease and identify as negative an uninfected person.

Next, the researchers piloted field tests in 50 visits at 27 schools from April 1 to May 25, 2022, to compare dogs’ detection ability with that of standard laboratory antigen testing. Participants in the completely voluntary screening numbered 1,558 and ranged in age from 9 to 17 years. Of these, 56% were girls and 89% were students. Almost 70% were screened at least twice.

Overall, the field test compared 3,897 paired antigen-vs.-dog screenings. The dogs accurately signaled the presence of 85 infections and ruled out 3,411 infections, for an overall accuracy of 90%. In 383 cases, however, they inaccurately signaled the presence of infection (false positives) and missed 18 actual infections (false negatives). That translated to a sensitivity in the field of 83%, considerably lower than that of their lab performance.

Direct screening of individuals with dogs outside of the lab involved circumstantial factors that likely contributed to decreased sensitivity and specificity, the authors acknowledged. These included such distractions as noise and the presence of excitable young children as well environmental conditions such as wind and other odors. What about dog phobia and dog hair allergy? “Dog screening takes only a few seconds per student and the dogs do not generally touch the participant as they run a line and sniff at ankles,” Dr. Glaser explained.

As for allergies, the rapid, ankle-level screening occurred in outdoor settings. “The chance of allergies is very low. This would be similar to someone who is out walking on the sidewalk and walks by a dog,” Dr. Glaser said.

Last year, a British trial of almost 4,000 adults tested six dogs trained to detect differences in VOCs between COVID-infected and uninfected individuals. Given samples from both groups, the dogs were able to distinguish between infected and uninfected samples with a sensitivity for detecting the virus ranging from 82% to 94% and a specificity for ruling it out of 76% to 92%. And they were able to smell the VOCs even when the viral load was low. The study also tested organic sensors, which proved even more accurate than the canines.

According to lead author James G. Logan, PhD, a disease control expert at the London School of Hygiene & Tropical Medicine in London, “Odour-based diagnostics using dogs and/or sensors may prove a rapid and effective tool for screening large numbers of people. Mathematical modelling suggests that dog screening plus a confirmatory PCR test could detect up to 89% of SARS-CoV-2 infections, averting up to 2.2 times as much transmission compared to isolation of symptomatic individuals only.”

Funding was provided by the Centers for Disease Control and Prevention Foundation (CDCF) to Early Alert Canines for the purchase and care of the dogs and the support of the handlers and trainers. The CDCF had no other role in the study. Coauthor Carol A. Edwards of Early Alert Canines reported receiving grants from the CDCF.

Scent-detecting dogs have long been used to sniff out medical conditions ranging from low blood sugar and cancer to malaria, impending seizures, and migraines – not to mention explosives and narcotics.

Recently, the sensitivity of the canine nose has been tested as a strategy for screening for SARS-CoV-2 infection in schoolchildren showing no outward symptoms of the virus. A pilot study led by Carol A. Glaser, DVM, MD, of the California Department of Public Health in Richmond, found that trained dogs had an accuracy of more than 95% for detecting the odor of volatile organic compounds, or VOCs, produced by COVID-infected individuals.

California Department of Public Health

The authors believe that odor-based diagnosis with dogs could eventually provide a rapid, inexpensive, and noninvasive way to screen large groups for COVID-19 without the need for antigen testing.

“This is a new program with research ongoing, so it would be premature to consider it from a consumer’s perspective,” Dr. Glaser said in an interview. “However, the data look promising and we are hopeful we can continue to pilot various programs in various settings to see where, and if, dogs can be used for biomedical detection.”
 

In the lab and in the field

In a study published online in JAMA Pediatrics, Dr. Glaser’s group found that after 2 months’ training on COVID-19 scent samples in the laboratory, the dogs detected the presence of the virus more than 95% of the time. Antigen tests were used as a comparative reference.

In medical terms, the dogs achieved a greater than 95% accuracy on two important measures of effectiveness: sensitivity – a test’s ability to correctly detect the positive presence of disease – and specificity – the ability of a test to accurately rule out the presence of disease and identify as negative an uninfected person.

Next, the researchers piloted field tests in 50 visits at 27 schools from April 1 to May 25, 2022, to compare dogs’ detection ability with that of standard laboratory antigen testing. Participants in the completely voluntary screening numbered 1,558 and ranged in age from 9 to 17 years. Of these, 56% were girls and 89% were students. Almost 70% were screened at least twice.

Overall, the field test compared 3,897 paired antigen-vs.-dog screenings. The dogs accurately signaled the presence of 85 infections and ruled out 3,411 infections, for an overall accuracy of 90%. In 383 cases, however, they inaccurately signaled the presence of infection (false positives) and missed 18 actual infections (false negatives). That translated to a sensitivity in the field of 83%, considerably lower than that of their lab performance.

Direct screening of individuals with dogs outside of the lab involved circumstantial factors that likely contributed to decreased sensitivity and specificity, the authors acknowledged. These included such distractions as noise and the presence of excitable young children as well environmental conditions such as wind and other odors. What about dog phobia and dog hair allergy? “Dog screening takes only a few seconds per student and the dogs do not generally touch the participant as they run a line and sniff at ankles,” Dr. Glaser explained.

As for allergies, the rapid, ankle-level screening occurred in outdoor settings. “The chance of allergies is very low. This would be similar to someone who is out walking on the sidewalk and walks by a dog,” Dr. Glaser said.

Last year, a British trial of almost 4,000 adults tested six dogs trained to detect differences in VOCs between COVID-infected and uninfected individuals. Given samples from both groups, the dogs were able to distinguish between infected and uninfected samples with a sensitivity for detecting the virus ranging from 82% to 94% and a specificity for ruling it out of 76% to 92%. And they were able to smell the VOCs even when the viral load was low. The study also tested organic sensors, which proved even more accurate than the canines.

According to lead author James G. Logan, PhD, a disease control expert at the London School of Hygiene & Tropical Medicine in London, “Odour-based diagnostics using dogs and/or sensors may prove a rapid and effective tool for screening large numbers of people. Mathematical modelling suggests that dog screening plus a confirmatory PCR test could detect up to 89% of SARS-CoV-2 infections, averting up to 2.2 times as much transmission compared to isolation of symptomatic individuals only.”

Funding was provided by the Centers for Disease Control and Prevention Foundation (CDCF) to Early Alert Canines for the purchase and care of the dogs and the support of the handlers and trainers. The CDCF had no other role in the study. Coauthor Carol A. Edwards of Early Alert Canines reported receiving grants from the CDCF.

Scent-detecting dogs have long been used to sniff out medical conditions ranging from low blood sugar and cancer to malaria, impending seizures, and migraines – not to mention explosives and narcotics.

Recently, the sensitivity of the canine nose has been tested as a strategy for screening for SARS-CoV-2 infection in schoolchildren showing no outward symptoms of the virus. A pilot study led by Carol A. Glaser, DVM, MD, of the California Department of Public Health in Richmond, found that trained dogs had an accuracy of more than 95% for detecting the odor of volatile organic compounds, or VOCs, produced by COVID-infected individuals.

California Department of Public Health

The authors believe that odor-based diagnosis with dogs could eventually provide a rapid, inexpensive, and noninvasive way to screen large groups for COVID-19 without the need for antigen testing.

“This is a new program with research ongoing, so it would be premature to consider it from a consumer’s perspective,” Dr. Glaser said in an interview. “However, the data look promising and we are hopeful we can continue to pilot various programs in various settings to see where, and if, dogs can be used for biomedical detection.”
 

In the lab and in the field

In a study published online in JAMA Pediatrics, Dr. Glaser’s group found that after 2 months’ training on COVID-19 scent samples in the laboratory, the dogs detected the presence of the virus more than 95% of the time. Antigen tests were used as a comparative reference.

In medical terms, the dogs achieved a greater than 95% accuracy on two important measures of effectiveness: sensitivity – a test’s ability to correctly detect the positive presence of disease – and specificity – the ability of a test to accurately rule out the presence of disease and identify as negative an uninfected person.

Next, the researchers piloted field tests in 50 visits at 27 schools from April 1 to May 25, 2022, to compare dogs’ detection ability with that of standard laboratory antigen testing. Participants in the completely voluntary screening numbered 1,558 and ranged in age from 9 to 17 years. Of these, 56% were girls and 89% were students. Almost 70% were screened at least twice.

Overall, the field test compared 3,897 paired antigen-vs.-dog screenings. The dogs accurately signaled the presence of 85 infections and ruled out 3,411 infections, for an overall accuracy of 90%. In 383 cases, however, they inaccurately signaled the presence of infection (false positives) and missed 18 actual infections (false negatives). That translated to a sensitivity in the field of 83%, considerably lower than that of their lab performance.

Direct screening of individuals with dogs outside of the lab involved circumstantial factors that likely contributed to decreased sensitivity and specificity, the authors acknowledged. These included such distractions as noise and the presence of excitable young children as well environmental conditions such as wind and other odors. What about dog phobia and dog hair allergy? “Dog screening takes only a few seconds per student and the dogs do not generally touch the participant as they run a line and sniff at ankles,” Dr. Glaser explained.

As for allergies, the rapid, ankle-level screening occurred in outdoor settings. “The chance of allergies is very low. This would be similar to someone who is out walking on the sidewalk and walks by a dog,” Dr. Glaser said.

Last year, a British trial of almost 4,000 adults tested six dogs trained to detect differences in VOCs between COVID-infected and uninfected individuals. Given samples from both groups, the dogs were able to distinguish between infected and uninfected samples with a sensitivity for detecting the virus ranging from 82% to 94% and a specificity for ruling it out of 76% to 92%. And they were able to smell the VOCs even when the viral load was low. The study also tested organic sensors, which proved even more accurate than the canines.

According to lead author James G. Logan, PhD, a disease control expert at the London School of Hygiene & Tropical Medicine in London, “Odour-based diagnostics using dogs and/or sensors may prove a rapid and effective tool for screening large numbers of people. Mathematical modelling suggests that dog screening plus a confirmatory PCR test could detect up to 89% of SARS-CoV-2 infections, averting up to 2.2 times as much transmission compared to isolation of symptomatic individuals only.”

Funding was provided by the Centers for Disease Control and Prevention Foundation (CDCF) to Early Alert Canines for the purchase and care of the dogs and the support of the handlers and trainers. The CDCF had no other role in the study. Coauthor Carol A. Edwards of Early Alert Canines reported receiving grants from the CDCF.