Impact of maternal diphtheria-tetanus-acellular pertussis vaccination on pertussis booster immune responses in toddlers: Follow-up of a randomized trial

Transplacentally transferred antibodies induced by maternal pertussis vaccination interfere with infant immune responses to primary vaccination. We evaluated whether this interference remains in toddlers after booster In a prior phase IV, observer-blind, placebo-controlled, randomized study (NCT02377349), pregnant women Australia, Canada and Europe received intramuscular tetanus-reduced-antigen-content diphtheria-three-component acellular vaccine (Tdap group) or placebo (control at 270/7–366/7 weeks’ gestation, crossover immunization postpartum. Their infants were primed (study NCT02422264) boosted (at 11–18 months; current NCT02853929) diphtheria-tetanus-three-component pertussis-hepatitis B virus-inactivated poliovirus/Haemophilus influenzae type b (DTaP-HepB-IPV/Hib) 13-valent pneumococcal conjugate vaccine. Immunogenicity before vaccination, reactogenicity safety of the descriptively. 263 277 DTaP-HepB-IPV/Hib booster. Pre-booster observed geometric mean concentrations (GMCs) for three antigens diphtheria 1.4–1.5-fold higher controls than Tdap group. No differences other antigens. One month post-booster response rates ≥ 92.1% seroprotection 99.2% both groups (primary objective). Higher GMCs versus group anti-filamentous hemagglutinin (1.2-fold), anti-pertussis toxoid (1.5-fold) anti-diphtheria (1.4-fold). similar between groups. Serious adverse events reported (controls, not vaccination-related). death occurred pre-booster group, As consequence antibody still lower from Tdap-vaccinated mothers After booster, filamentous but pertactin. The clinical significance requires further evaluation. Clinical Trial Registration. ClinicalTrials.gov: NCT02853929.