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

Abstract

Background: Vaccination in pregnancy with recombinant pertussis vaccine results in similar or higher antibody levels in infants compared with chemically detoxified acellular pertussis vaccine (Tdapchem). 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 (ap1gen, Tdap1gen, Tdap2gen or TdaP5gen) or Tdapchem. 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.