DTaP Vaccine's Strong Prevention of Whooping Cough May Wane Over Time

A study in the July 2019 Pediatrics, “Acellular Pertussis Vaccine Effectiveness Over Time,” found that children were more likely to get pertussis as time passed since their last dose of the vaccine. For the study, published online June 10, researchers tracked 469,982 children born between 1999 and 2016 and found the vast majority received the diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccines. Only 1% were unvaccinated and 3% under-vaccinated (children with fewer doses than expected for their age). During that period there were 738 pertussis cases in this study group: 99 children (13%) of those who got whooping cough were from the 1% who were unvaccinated, 36 (5%) were under-vaccinated, 515 (70%) were fully vaccinated, and 88 (12%) were fully vaccinated plus one dose. Researchers found that some children had more than the recommended doses because their risk of pertussis may be different. The 26% of children who were vaccinated plus one dose had a lower risk of pertussis compared with fully vaccinated children. Conversely, partially vaccinated children were almost twice as likely to get pertussis. Researchers also found that vaccinated children who had received their last DTaP dose years earlier were at increased risk of pertussis compared to those who had received the shot more recently. Researchers concluded that while the DTaP vaccine offered substantial protections against whooping cough, suboptimal vaccine effectiveness and waning over time played a major role in recent pertussis outbreaks.

Editor’s Note: A solicited commentary, “Challenges for Pertussis Control,” will be published in the same issue of Pediatrics.

###

The American Academy of Pediatrics is an organization of 67,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults. For more information, visit www.aap.org and follow us on Twitter @AmerAcadPeds