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

Abstract

Background: Transplacentally transferred antibodies induced by maternal pertussis vaccination interfere with infant immune responses to pertussis primary vaccination. We evaluated whether this interference remains in toddlers after booster vaccination.

Methods: In a prior phase IV, observer-blind, placebo-controlled, randomized study (NCT02377349), pregnant women in Australia, Canada and Europe received intramuscular tetanus-reduced-antigen-content diphtheria-three-component acellular pertussis vaccine (Tdap group) or placebo (control group) at 270/7-366/7 weeks' gestation, with crossover immunization postpartum. Their infants were primed (study NCT02422264) and boosted (at 11-18 months; current study NCT02853929) with diphtheria-tetanus-three-component acellular pertussis-hepatitis B virus-inactivated poliovirus/Haemophilus influenzae type b vaccine (DTaP-HepB-IPV/Hib) and 13-valent pneumococcal conjugate vaccine. Immunogenicity before and after booster vaccination, and reactogenicity and safety of the booster were evaluated descriptively.

Results: 263 (Tdap group) and 277 (control group) toddlers received a DTaP-HepB-IPV/Hib booster. Pre-booster vaccination, observed geometric mean concentrations (GMCs) for the three pertussis antigens and diphtheria were 1.4-1.5-fold higher in controls than in the Tdap group. No differences were observed for the other DTaP-HepB-IPV/Hib antigens. One month post-booster vaccination, booster response rates for pertussis antigens were ≥ 92.1% and seroprotection rates for the other DTaP-HepB-IPV/Hib antigens were ≥ 99.2% in both groups (primary objective). Higher post-booster GMCs were observed in controls versus the Tdap group for anti-filamentous hemagglutinin (1.2-fold), anti-pertussis toxoid (1.5-fold) and anti-diphtheria (1.4-fold). GMCs for the other DTaP-HepB-IPV/Hib antigens were similar between groups. Serious adverse events were reported for three toddlers (controls, not vaccination-related). One death occurred pre-booster (Tdap group, not vaccination-related).

Conclusions: As a consequence of interference of maternal pertussis antibodies with infant immune responses to pertussis primary vaccination, pertussis antibody concentrations were still lower in toddlers from Tdap-vaccinated mothers before DTaP-HepB-IPV/Hib booster vaccination. After the booster, antibody concentrations were lower for filamentous hemagglutinin and pertussis toxoid but not for pertactin. The clinical significance of this interference requires further evaluation.

Clinical trial registration: ClinicalTrials.gov: NCT02853929.

Keywords: Blunting; Booster; Maternal immunization; Pertussis; Tdap vaccine; Toddlers.

Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: BAN reports grants from the GSK group of companies (GSK) and support from other vaccine manufacturers. BC, MAC, NMes, NMey and SOK are employees of GSK, and BC, MAC and NMes own GSK restricted shares. FMT, JGS, SAH, TN and KPP’s institutions received grants from GSK during the conduct of the study. FMT’s institution received financial and non-financial support from Ablynx, Astra Zeneca, GSK, Jansen, MedImmune, MSD, Novavax, Pfizer, Regeneron, Roche, Sanofi Pasteur and Seqirus outside the submitted work. SAH received honoraria for participation in ad-hoc advisory committees for GSK and Sanofi Pasteur. TN received personal fees from GSK for serving as chair of advisory committees outside the submitted work. BT’s institution received grants from GSK during the conduct of the study; research grants for clinical trials were also given to his institution by Pfizer, MSD and Sanofi Pasteur. KPP received a fellowship from National Health and Medical Research Council for conducting the present work, and her institution received financial support from DBV Technologies, Medlmmune, Novavax and Pfizer for conducting trials outside the submitted work. ISC has received grants and/or honoraria as a consultant/advisor or to attend conferences and practical courses from GSK, Sanofi Pasteur, MSD and Pfizer outside the submitted work. JMMA reports receiving fees and non-financial support from GSK, as well as fees from Pfizer and MSD outside the submitted work. LK is working as consultant for GSK. MB, JB, MJCO, EEP, JJ, MMV, PK, PGM, JTRA, SR, ZS, MV, OGV and GVZ declare no conflicts of interest.

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