Objective: To compare the reactogenicity and immune response to the Takeda acellular pertussis-component diphtheria-tetanus-pertussis (APDT) vaccine in children when immunization commenced at 2 months (group A) vs 3 months (group B) of age.
Design: Longitudinal, nonblinded, comparative study.
Setting: Pediatric well-child clinics.
Participants: Healthy 50- to 98-day-old infants.
Results: Good antibody responses to lymphocytosis-promoting factor, filamentous hemagglutinin, agglutinogens, and pertactin occurred in both age groups after both the third and fourth vaccine doses. Both young age and transplacentally acquired maternal antibody independently and together have a suppressive effect on the response to the four antigens in this APDT vaccine. However, these effects appear to be minor. Vaccine reactions were mild; group A children had slightly but not significantly higher rates than group B children.
Conclusion: The present US diphtheria and tetanus toxoids and pertussis vaccine immunization schedule should also be satisfactory with this acellular pertussis component vaccine.