Objective: To assess antibody persistence and booster immunogenicity and safety of a new, fully liquid, hexavalent DTaP-IPV-Hep B-PRP-T vaccine.
Methods: Phase III, open-label, 2-center trial. Infants previously primed at 6, 10, 14 weeks of age with DTaP-IPV-Hep B-PRP-T either without (group 1: N = 218) or with hepatitis B at birth (group 3: N = 130) or control DTwP-Hib, hepatitis B and oral poliovirus vaccine vaccines (group 2: N = 219) received the same vaccine(s) as booster (except hepatitis B for group 2) at 15-18 months of age, coadministered with measles/mumps/rubella and varicella vaccines (MMR+V). All participants had received measles vaccine at 9 months of age. Antibodies were measured prebooster and 1 month postbooster vaccination. Safety was evaluated from parental reports. Analyses were descriptive.
Results: Antibody persistence (seroprotection and concentration) at 15-18 months of age was high for each valence and similar in each group, except for Hep B (highest in group 3 [extra dose of hepatitis B]) and PRP (highest in group 2). Postbooster seroprotection (D, T, IPV, Hep B, PRP) and seroconversion (pertussis toxin and filamentous hemagglutinin) rates were high and similar in each group (excluding Hep B in group 2 [no booster]); geometric mean antibody levels increased markedly in all groups. The response to MMR+V was similar in each group. All vaccines were well tolerated.
Conclusions: A booster dose of the new DTaP-IPV-Hep B-PRP-T vaccine at 15-18 months of age is highly immunogenic and safe compared with licensed comparators, following primary series administration in the Expanded Program on Immunization schedule, with or without a hepatitis B vaccine at birth and coadministered with MMR+V.