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A sixth dose of Tdap is initially effective in preventing pertussis in teens, but its effectiveness declines by half within 4 years after the booster, a recent study found.
“This waning is likely contributing to the increase in pertussis among adolescents,” reported Dr. Anna M. Acosta of the Centers for Disease Control and Prevention, Atlanta, and her associates (Pediatrics 2015 [doi: 10.1542/peds.2014-3358]).
“Advances in our understanding of the immunology and bacteriology of Bordetella pertussis are essential to optimize future prevention and control measures,” they wrote. “However, novel pertussis vaccines that effectively limit infection and transmission are also likely needed to reduce the burden of pertussis disease in the United States.”
The researchers matched three controls by birth year and primary provider practice (total 2,322 controls) to each of 836 cases of pertussis in seven counties of Washington during the 2012 pertussis epidemic. Cases were more likely than were controls to be non-Hispanic and white, but there was a lack of race/ethnicity data.
Receipt of the five childhood series doses was similar among cases (74%) and controls (75%), but a smaller proportion of both (60% cases, 58% controls) were on schedule. Among more than 84% of participants who received Tdap between ages 11 and 12, 81% of the cases and 90% of the controls received the sixth dose.
Among the 450 cases and 1,246 controls who received all acellular vaccines for the primary series, Tdap effectiveness was 63.9% overall. Stratified by time since Tdap vaccination, however, it was 73.1% within 12 months, 54.9% within 12-23 months, and 34.2% within 24-47 months.
Those born from 1999 to 2000 were presumed to have received the DTaP in infancy, and those born from 1993 to 1997 were presumed to have received a mixture of the acellular and whole-cell (DTwP) vaccines. Among those with vaccine lot numbers recorded, all vaccines administered after 1998 were acellular. A direct comparison of Tdap effectiveness between those vaccinated with the acellular primary series and those vaccinated with a mixed primary series was not possible because of time differences in vaccination between the two groups.
The research did not receive external funding, and the authors reported no relevant financial disclosures.
In the study by Acosta et al., the duration of Tdap effectiveness is disappointing, particularly because case-control studies tend to inflate efficacy. The resurgence of pertussis is often attributed to the switch from whole-cell pertussis vaccines to acellular products. However, the increase in reported pertussis began 14 years before the universal use of diphtheria-tetanus-acellular pertussis (DTaP) vaccines in childhood commenced. The two greatest contributors to the resurgence of pertussis are greater awareness and more sensitive diagnosis (routine use of polymerase chain reaction).
In the pre-DTaP and pre-Tdap eras, the pertussis attack rate in nonepidemic periods in largely whole-cell pertussis vaccine–primed adolescents and adults was 370 to 500 per 100,000 per year. These rates are underestimates because of clear evidence of “observer bias” in both studies. In this present Washington State study, the attack rate during the epidemic was only 182.3 per 100,000 for the one-half-year study period.
Factors that I think are most important relating to DTaP vaccine failure are as follows: decay in antibody over time; a T helper (Th) 1/Th2 versus a Th1, Th17 cellular response; incomplete antigen package; incorrect balance of antigens in the vaccine; linked-epitope suppression; and the occurrence of pertactin-deficient B. pertussis strains. Some, but not all, of these factors also may relate to Tdap failure over time.
Although adequate data are not available, it can be assumed that adolescents and adults who were primed in infancy by infection or DTP will have a Th1, Th17 response to Tdap. In contrast, those who were primed by DTaP will have a Th1/Th2 response. In line with the results of these two recent Tdap effectiveness studies, we should examine our present Tdap immunization recommendations. It is my opinion that we should continue with our present Tdap schedules. Of most importance is to see that all pregnant women receive Tdap with each pregnancy. This alone can prevent virtually all pertussis deaths in young infants.
James D. Cherry, M.D., is professor of pediatrics at the University of California, Los Angeles. These comments are excerpted from an editorial (Pediatrics 2015 [doi:10.1542/peds.2014-4118]) accompanying Dr. Acosta’s study. Dr. Cherry is a member of the Sanofi Pasteur speakers bureau and of the Global Pertussis Initiative, supported by Sanofi Pastuer. He receives royalties from Elsevier for “Feigin and Cherry’s Textbook of Pediatric Infectious Diseases.”
In the study by Acosta et al., the duration of Tdap effectiveness is disappointing, particularly because case-control studies tend to inflate efficacy. The resurgence of pertussis is often attributed to the switch from whole-cell pertussis vaccines to acellular products. However, the increase in reported pertussis began 14 years before the universal use of diphtheria-tetanus-acellular pertussis (DTaP) vaccines in childhood commenced. The two greatest contributors to the resurgence of pertussis are greater awareness and more sensitive diagnosis (routine use of polymerase chain reaction).
In the pre-DTaP and pre-Tdap eras, the pertussis attack rate in nonepidemic periods in largely whole-cell pertussis vaccine–primed adolescents and adults was 370 to 500 per 100,000 per year. These rates are underestimates because of clear evidence of “observer bias” in both studies. In this present Washington State study, the attack rate during the epidemic was only 182.3 per 100,000 for the one-half-year study period.
Factors that I think are most important relating to DTaP vaccine failure are as follows: decay in antibody over time; a T helper (Th) 1/Th2 versus a Th1, Th17 cellular response; incomplete antigen package; incorrect balance of antigens in the vaccine; linked-epitope suppression; and the occurrence of pertactin-deficient B. pertussis strains. Some, but not all, of these factors also may relate to Tdap failure over time.
Although adequate data are not available, it can be assumed that adolescents and adults who were primed in infancy by infection or DTP will have a Th1, Th17 response to Tdap. In contrast, those who were primed by DTaP will have a Th1/Th2 response. In line with the results of these two recent Tdap effectiveness studies, we should examine our present Tdap immunization recommendations. It is my opinion that we should continue with our present Tdap schedules. Of most importance is to see that all pregnant women receive Tdap with each pregnancy. This alone can prevent virtually all pertussis deaths in young infants.
James D. Cherry, M.D., is professor of pediatrics at the University of California, Los Angeles. These comments are excerpted from an editorial (Pediatrics 2015 [doi:10.1542/peds.2014-4118]) accompanying Dr. Acosta’s study. Dr. Cherry is a member of the Sanofi Pasteur speakers bureau and of the Global Pertussis Initiative, supported by Sanofi Pastuer. He receives royalties from Elsevier for “Feigin and Cherry’s Textbook of Pediatric Infectious Diseases.”
In the study by Acosta et al., the duration of Tdap effectiveness is disappointing, particularly because case-control studies tend to inflate efficacy. The resurgence of pertussis is often attributed to the switch from whole-cell pertussis vaccines to acellular products. However, the increase in reported pertussis began 14 years before the universal use of diphtheria-tetanus-acellular pertussis (DTaP) vaccines in childhood commenced. The two greatest contributors to the resurgence of pertussis are greater awareness and more sensitive diagnosis (routine use of polymerase chain reaction).
In the pre-DTaP and pre-Tdap eras, the pertussis attack rate in nonepidemic periods in largely whole-cell pertussis vaccine–primed adolescents and adults was 370 to 500 per 100,000 per year. These rates are underestimates because of clear evidence of “observer bias” in both studies. In this present Washington State study, the attack rate during the epidemic was only 182.3 per 100,000 for the one-half-year study period.
Factors that I think are most important relating to DTaP vaccine failure are as follows: decay in antibody over time; a T helper (Th) 1/Th2 versus a Th1, Th17 cellular response; incomplete antigen package; incorrect balance of antigens in the vaccine; linked-epitope suppression; and the occurrence of pertactin-deficient B. pertussis strains. Some, but not all, of these factors also may relate to Tdap failure over time.
Although adequate data are not available, it can be assumed that adolescents and adults who were primed in infancy by infection or DTP will have a Th1, Th17 response to Tdap. In contrast, those who were primed by DTaP will have a Th1/Th2 response. In line with the results of these two recent Tdap effectiveness studies, we should examine our present Tdap immunization recommendations. It is my opinion that we should continue with our present Tdap schedules. Of most importance is to see that all pregnant women receive Tdap with each pregnancy. This alone can prevent virtually all pertussis deaths in young infants.
James D. Cherry, M.D., is professor of pediatrics at the University of California, Los Angeles. These comments are excerpted from an editorial (Pediatrics 2015 [doi:10.1542/peds.2014-4118]) accompanying Dr. Acosta’s study. Dr. Cherry is a member of the Sanofi Pasteur speakers bureau and of the Global Pertussis Initiative, supported by Sanofi Pastuer. He receives royalties from Elsevier for “Feigin and Cherry’s Textbook of Pediatric Infectious Diseases.”
A sixth dose of Tdap is initially effective in preventing pertussis in teens, but its effectiveness declines by half within 4 years after the booster, a recent study found.
“This waning is likely contributing to the increase in pertussis among adolescents,” reported Dr. Anna M. Acosta of the Centers for Disease Control and Prevention, Atlanta, and her associates (Pediatrics 2015 [doi: 10.1542/peds.2014-3358]).
“Advances in our understanding of the immunology and bacteriology of Bordetella pertussis are essential to optimize future prevention and control measures,” they wrote. “However, novel pertussis vaccines that effectively limit infection and transmission are also likely needed to reduce the burden of pertussis disease in the United States.”
The researchers matched three controls by birth year and primary provider practice (total 2,322 controls) to each of 836 cases of pertussis in seven counties of Washington during the 2012 pertussis epidemic. Cases were more likely than were controls to be non-Hispanic and white, but there was a lack of race/ethnicity data.
Receipt of the five childhood series doses was similar among cases (74%) and controls (75%), but a smaller proportion of both (60% cases, 58% controls) were on schedule. Among more than 84% of participants who received Tdap between ages 11 and 12, 81% of the cases and 90% of the controls received the sixth dose.
Among the 450 cases and 1,246 controls who received all acellular vaccines for the primary series, Tdap effectiveness was 63.9% overall. Stratified by time since Tdap vaccination, however, it was 73.1% within 12 months, 54.9% within 12-23 months, and 34.2% within 24-47 months.
Those born from 1999 to 2000 were presumed to have received the DTaP in infancy, and those born from 1993 to 1997 were presumed to have received a mixture of the acellular and whole-cell (DTwP) vaccines. Among those with vaccine lot numbers recorded, all vaccines administered after 1998 were acellular. A direct comparison of Tdap effectiveness between those vaccinated with the acellular primary series and those vaccinated with a mixed primary series was not possible because of time differences in vaccination between the two groups.
The research did not receive external funding, and the authors reported no relevant financial disclosures.
A sixth dose of Tdap is initially effective in preventing pertussis in teens, but its effectiveness declines by half within 4 years after the booster, a recent study found.
“This waning is likely contributing to the increase in pertussis among adolescents,” reported Dr. Anna M. Acosta of the Centers for Disease Control and Prevention, Atlanta, and her associates (Pediatrics 2015 [doi: 10.1542/peds.2014-3358]).
“Advances in our understanding of the immunology and bacteriology of Bordetella pertussis are essential to optimize future prevention and control measures,” they wrote. “However, novel pertussis vaccines that effectively limit infection and transmission are also likely needed to reduce the burden of pertussis disease in the United States.”
The researchers matched three controls by birth year and primary provider practice (total 2,322 controls) to each of 836 cases of pertussis in seven counties of Washington during the 2012 pertussis epidemic. Cases were more likely than were controls to be non-Hispanic and white, but there was a lack of race/ethnicity data.
Receipt of the five childhood series doses was similar among cases (74%) and controls (75%), but a smaller proportion of both (60% cases, 58% controls) were on schedule. Among more than 84% of participants who received Tdap between ages 11 and 12, 81% of the cases and 90% of the controls received the sixth dose.
Among the 450 cases and 1,246 controls who received all acellular vaccines for the primary series, Tdap effectiveness was 63.9% overall. Stratified by time since Tdap vaccination, however, it was 73.1% within 12 months, 54.9% within 12-23 months, and 34.2% within 24-47 months.
Those born from 1999 to 2000 were presumed to have received the DTaP in infancy, and those born from 1993 to 1997 were presumed to have received a mixture of the acellular and whole-cell (DTwP) vaccines. Among those with vaccine lot numbers recorded, all vaccines administered after 1998 were acellular. A direct comparison of Tdap effectiveness between those vaccinated with the acellular primary series and those vaccinated with a mixed primary series was not possible because of time differences in vaccination between the two groups.
The research did not receive external funding, and the authors reported no relevant financial disclosures.
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