Why Do Pertussis Vaccines Fail?
James D. Cherry, MD, MSc
Pediatric Infectious Diseases, Mattel Children’s Hospital University of California Los Angeles, and the Department of Pediatrics, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, California
adolescent- and adult-formulated tetanus and diphtheria toxoids and acellular pertussis vaccine
•Abbreviations: DTaP — pediatric diphtheria and tetanus toxoids and acellular pertussis vaccineDTP — pediatric diphtheria and tetanus toxoids and whole-cell pertussis vaccineFHA — filamentous hemagglutininFIM — fimbriaePCR — polymerase chain reactionPRN — pertactinPT — pertussis toxinWHO — World Health Organization
Possible Reasons Why DTP, DTaP, and Adolescent- and Adult-Formulated Tetanus and Diphtheria Toxoids and Acellular Pertussis Vaccines Fail
The first reason, and perhaps the most important one, is that our estimates of vaccine efficacy have been inflated because of case definition.3–11 At the time of the pediatric diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine efficacy trials in the early 1990s, it was hoped that a universal case definition could be developed so that the results of the various trials could be compared. To this end, the World Health Organization (WHO) case definition was developed.3 The primary case definition required laboratory confirmation and ≥21 days of paroxysmal cough. I was a member of the WHO committee and disagreed with the primary case definition because it was clear at that time that this definition would eliminate a substantial number of cases and therefore inflate reported efficacy values.4–11 Nevertheless, the Center for Biologics Evaluation and Research of the Food and Drug Administration accepted this definition, and package inserts of the US-licensed DTaP vaccines reflect this. For example, Infanrix (containing 25 μg pertussis toxin [PT], 25 μg filamentous hemagglutinin [FHA], and 8 μg pertactin [PRN]) and Daptacel (containing 10 μg PT, 5 μg FHA, 5 μg fimbriae [FIM]-2/3, and 3 μg