User login
In a placebo-controlled trial, an investigational vaccine protected a small but statistically significant proportion of healthy volunteers against naturally acquired malaria infection for the duration of the malaria season in Mali.
The vaccine, known as the PfSPZ Vaccine, contains live but weakened Plasmodium falciparum sporozoites and was developed by scientists at Sanaria Inc.
Results of the phase 1 trial were published in The Lancet Infectious Diseases.
Sanaria was the regulatory sponsor of the trial. The National Institute of Allergy and Infectious Diseases (NIAID) supported the development of the vaccine.
Earlier research suggested the PfSPZ Vaccine was safe and could protect against malaria infection for up to a year in healthy US adults who had not been previously exposed to malaria.
The Mali study was launched in January 2014 to provide additional safety data for the PfSPZ Vaccine and determine if it could protect adults living in a malaria-endemic area against naturally occurring malaria infection.
The study enrolled 109 healthy African men and non-pregnant women ages 18 to 35. Subjects received either 5 doses of the intravenous PfSPZ Vaccine (2.7 × 10⁵) or 5 doses of placebo (saline) over 5 months of the dry season at the study’s clinical site in the Donéguébougou village in rural Mali.
The subjects also received combined artemether and lumefantrine (4 tablets twice per day over 3 days) to eliminate P falciparum before the first and last vaccinations.
Clinical staff monitored the subjects during the 6-month malaria-transmission season for the presence of malaria parasites in the blood. The team collected blood smears every 2 weeks and during any illness for 24 weeks after the fifth vaccination.
The investigators said they detected no significant differences in local or systemic adverse events or laboratory abnormalities between the PfSPZ Vaccine group and the placebo group.
The most common solicited systemic adverse events were headache (7% in the vaccine group and 9% in the placebo group), fatigue (2% in the placebo group), fever (2% in the placebo group), and myalgia (2% in each group).
Efficacy
Ninety-three percent of evaluable subjects in the placebo group (37/40) and 66% of evaluable subjects in the PfSPZ Vaccine group (27/41) developed P falciparum malaria infections.
The investigators said the PfSPZ Vaccine demonstrated a 48% protective efficacy by time to first positive malaria blood smear and 29% efficacy by the proportion of participants with at least 1 positive malaria blood smear during a full 20-week malaria transmission season.
By both measures of protective efficacy, there was statistically significant protection in the vaccine group compared to the placebo group.
“This level of sustained efficacy against malaria infection in a region with an intense transmission season has not been seen in previous malaria vaccine studies in Africa,” said Sara Healy, MD, of NIAID in Bethesda, Maryland.
“It is a very encouraging finding that we can, hopefully, build upon.”
The investigators noted that the vaccine-induced antibody response was considerably lower in the Mali study than in the US trial, even though subjects received the same vaccine regimen.
“The poor antibody response to PfSPZ Vaccine among Malians could have been because of the participants’ lifelong exposure to P falciparum,” said Patrick E. Duffy, MD, of NIAID.
Feasibility
The investigators reported that there was no problem administering the PfSPZ Vaccine in a rural, malaria-endemic area—an initial concern about the vaccine’s design.
“Direct venous inoculation is not currently used for any licensed vaccines to prevent an infectious disease,” said Ogobara Doumbo, MD, PhD, of the University of Science, Techniques and Technologies of Bamako in Bamako, Mali.
“In this study, we administered 491 inoculations in a rural setting without a problem, and the dosages were delivered in a matter of seconds. It shows that this approach is feasible from both a logistical and public health standpoint.”
According to the investigators, a malaria vaccine employed in mass vaccination programs to eliminate P falciparum from geographically defined areas would need to prevent malaria infection or transmission in at least 80% of recipients throughout the malaria transmission season.
Clinical trials now underway in Africa, Europe, and the US have been designed to boost the PfSPZ Vaccine’s efficacy by increasing dosage levels and varying the timing and number of doses.
The experimental vaccine is also being examined in demographic groups other than healthy adults, including adolescents, children, and infants. 
In a placebo-controlled trial, an investigational vaccine protected a small but statistically significant proportion of healthy volunteers against naturally acquired malaria infection for the duration of the malaria season in Mali.
The vaccine, known as the PfSPZ Vaccine, contains live but weakened Plasmodium falciparum sporozoites and was developed by scientists at Sanaria Inc.
Results of the phase 1 trial were published in The Lancet Infectious Diseases.
Sanaria was the regulatory sponsor of the trial. The National Institute of Allergy and Infectious Diseases (NIAID) supported the development of the vaccine.
Earlier research suggested the PfSPZ Vaccine was safe and could protect against malaria infection for up to a year in healthy US adults who had not been previously exposed to malaria.
The Mali study was launched in January 2014 to provide additional safety data for the PfSPZ Vaccine and determine if it could protect adults living in a malaria-endemic area against naturally occurring malaria infection.
The study enrolled 109 healthy African men and non-pregnant women ages 18 to 35. Subjects received either 5 doses of the intravenous PfSPZ Vaccine (2.7 × 10⁵) or 5 doses of placebo (saline) over 5 months of the dry season at the study’s clinical site in the Donéguébougou village in rural Mali.
The subjects also received combined artemether and lumefantrine (4 tablets twice per day over 3 days) to eliminate P falciparum before the first and last vaccinations.
Clinical staff monitored the subjects during the 6-month malaria-transmission season for the presence of malaria parasites in the blood. The team collected blood smears every 2 weeks and during any illness for 24 weeks after the fifth vaccination.
The investigators said they detected no significant differences in local or systemic adverse events or laboratory abnormalities between the PfSPZ Vaccine group and the placebo group.
The most common solicited systemic adverse events were headache (7% in the vaccine group and 9% in the placebo group), fatigue (2% in the placebo group), fever (2% in the placebo group), and myalgia (2% in each group).
Efficacy
Ninety-three percent of evaluable subjects in the placebo group (37/40) and 66% of evaluable subjects in the PfSPZ Vaccine group (27/41) developed P falciparum malaria infections.
The investigators said the PfSPZ Vaccine demonstrated a 48% protective efficacy by time to first positive malaria blood smear and 29% efficacy by the proportion of participants with at least 1 positive malaria blood smear during a full 20-week malaria transmission season.
By both measures of protective efficacy, there was statistically significant protection in the vaccine group compared to the placebo group.
“This level of sustained efficacy against malaria infection in a region with an intense transmission season has not been seen in previous malaria vaccine studies in Africa,” said Sara Healy, MD, of NIAID in Bethesda, Maryland.
“It is a very encouraging finding that we can, hopefully, build upon.”
The investigators noted that the vaccine-induced antibody response was considerably lower in the Mali study than in the US trial, even though subjects received the same vaccine regimen.
“The poor antibody response to PfSPZ Vaccine among Malians could have been because of the participants’ lifelong exposure to P falciparum,” said Patrick E. Duffy, MD, of NIAID.
Feasibility
The investigators reported that there was no problem administering the PfSPZ Vaccine in a rural, malaria-endemic area—an initial concern about the vaccine’s design.
“Direct venous inoculation is not currently used for any licensed vaccines to prevent an infectious disease,” said Ogobara Doumbo, MD, PhD, of the University of Science, Techniques and Technologies of Bamako in Bamako, Mali.
“In this study, we administered 491 inoculations in a rural setting without a problem, and the dosages were delivered in a matter of seconds. It shows that this approach is feasible from both a logistical and public health standpoint.”
According to the investigators, a malaria vaccine employed in mass vaccination programs to eliminate P falciparum from geographically defined areas would need to prevent malaria infection or transmission in at least 80% of recipients throughout the malaria transmission season.
Clinical trials now underway in Africa, Europe, and the US have been designed to boost the PfSPZ Vaccine’s efficacy by increasing dosage levels and varying the timing and number of doses.
The experimental vaccine is also being examined in demographic groups other than healthy adults, including adolescents, children, and infants.
In a placebo-controlled trial, an investigational vaccine protected a small but statistically significant proportion of healthy volunteers against naturally acquired malaria infection for the duration of the malaria season in Mali.
The vaccine, known as the PfSPZ Vaccine, contains live but weakened Plasmodium falciparum sporozoites and was developed by scientists at Sanaria Inc.
Results of the phase 1 trial were published in The Lancet Infectious Diseases.
Sanaria was the regulatory sponsor of the trial. The National Institute of Allergy and Infectious Diseases (NIAID) supported the development of the vaccine.
Earlier research suggested the PfSPZ Vaccine was safe and could protect against malaria infection for up to a year in healthy US adults who had not been previously exposed to malaria.
The Mali study was launched in January 2014 to provide additional safety data for the PfSPZ Vaccine and determine if it could protect adults living in a malaria-endemic area against naturally occurring malaria infection.
The study enrolled 109 healthy African men and non-pregnant women ages 18 to 35. Subjects received either 5 doses of the intravenous PfSPZ Vaccine (2.7 × 10⁵) or 5 doses of placebo (saline) over 5 months of the dry season at the study’s clinical site in the Donéguébougou village in rural Mali.
The subjects also received combined artemether and lumefantrine (4 tablets twice per day over 3 days) to eliminate P falciparum before the first and last vaccinations.
Clinical staff monitored the subjects during the 6-month malaria-transmission season for the presence of malaria parasites in the blood. The team collected blood smears every 2 weeks and during any illness for 24 weeks after the fifth vaccination.
The investigators said they detected no significant differences in local or systemic adverse events or laboratory abnormalities between the PfSPZ Vaccine group and the placebo group.
The most common solicited systemic adverse events were headache (7% in the vaccine group and 9% in the placebo group), fatigue (2% in the placebo group), fever (2% in the placebo group), and myalgia (2% in each group).
Efficacy
Ninety-three percent of evaluable subjects in the placebo group (37/40) and 66% of evaluable subjects in the PfSPZ Vaccine group (27/41) developed P falciparum malaria infections.
The investigators said the PfSPZ Vaccine demonstrated a 48% protective efficacy by time to first positive malaria blood smear and 29% efficacy by the proportion of participants with at least 1 positive malaria blood smear during a full 20-week malaria transmission season.
By both measures of protective efficacy, there was statistically significant protection in the vaccine group compared to the placebo group.
“This level of sustained efficacy against malaria infection in a region with an intense transmission season has not been seen in previous malaria vaccine studies in Africa,” said Sara Healy, MD, of NIAID in Bethesda, Maryland.
“It is a very encouraging finding that we can, hopefully, build upon.”
The investigators noted that the vaccine-induced antibody response was considerably lower in the Mali study than in the US trial, even though subjects received the same vaccine regimen.
“The poor antibody response to PfSPZ Vaccine among Malians could have been because of the participants’ lifelong exposure to P falciparum,” said Patrick E. Duffy, MD, of NIAID.
Feasibility
The investigators reported that there was no problem administering the PfSPZ Vaccine in a rural, malaria-endemic area—an initial concern about the vaccine’s design.
“Direct venous inoculation is not currently used for any licensed vaccines to prevent an infectious disease,” said Ogobara Doumbo, MD, PhD, of the University of Science, Techniques and Technologies of Bamako in Bamako, Mali.
“In this study, we administered 491 inoculations in a rural setting without a problem, and the dosages were delivered in a matter of seconds. It shows that this approach is feasible from both a logistical and public health standpoint.”
According to the investigators, a malaria vaccine employed in mass vaccination programs to eliminate P falciparum from geographically defined areas would need to prevent malaria infection or transmission in at least 80% of recipients throughout the malaria transmission season.
Clinical trials now underway in Africa, Europe, and the US have been designed to boost the PfSPZ Vaccine’s efficacy by increasing dosage levels and varying the timing and number of doses.
The experimental vaccine is also being examined in demographic groups other than healthy adults, including adolescents, children, and infants.