Infant Responses to Primary Immunization Following Vaccination in Pregnancy With Varying Doses of Recombinant Acellular Pertussis Vaccine Alone or Combined With Tetanus-Diphtheria

Background: Vaccination in pregnancy with recombinant pertussis vaccine results in similar or higher antibody levels in infants compared with chemically detoxified acellular pertussis vaccine (Tdap_chem). We evaluated antibody responses to primary childhood vaccination in infants born to mothers vaccinated in pregnancy with recombinant pertussis vaccine containing 1, 2 or 5 µg genetically detoxified pertussis toxin (ap1_gen, Tdap1_gen, Tdap2_gen or TdaP5_gen) or Tdap_chem. Methods: Infants (393) received diphtheria-tetanus-whole cell pertussis (DTwP) at 2, 4 and 6 months (3+0) and 13-valent pneumococcal conjugate vaccine (PCV13) at 2, 4 and 12 months of age (2+1). Serum IgG levels against pertussis toxoid (PT), filamentous hemagglutinin (FHA), diphtheria toxoid (DT), tetanus toxoid (TT), PCV13 serotypes and PT-neutralizing antibody (PT-Nab) titers were assessed. PT-IgG ≥10 IU was used as a cutoff for potential protection in infants. Results: PT-IgG geometric mean concentrations (GMC) were ≥10 IU/ mL at 5 and 7 months of age but waned below 10 IU/mL at 13 months in all groups. FHA-IgG GMCs and PT-Nab geometric mean titers were also below 10 IU/mL in all groups at 13 months of age. TT-IgG and DT-IgG seroprotection rates (≥0.1 IU/mL) ranged from 97.1% to 100% at 7 and 13 months. Postbooster PCV13-serotype-specific seroprotection rates (IgG ≥ 0.35 µg/mL) ranged between 87% and 100%. Antibody responses were comparable between groups after DTwP priming (7 months) and PCV13 priming (5 months) and booster vaccination (13 months). Conclusions: Childhood vaccine responses are comparable after mothers receive genetically or chemically detoxified acellular pertussis vaccines in pregnancy.