Transplacental transfer of maternal antibodies following immunization with recombinant pertussis vaccines during pregnancy: real-world evidence.

AIM/OBJECTIVE: This study investigates placental antibody transfer following recombinant pertussis vaccination in pregnancy in a real-world setting.

METHODS: This post-marketing observational study recruited pregnant women vaccinated with monovalent recombinant acellular pertussis vaccine (aPgen ; n=199) or combined to tetanus-diphtheria (TdaPgen ; n=200), or Td-vaccine only (n=54). Pregnancy, delivery, and neonatal outcomes were assessed. Cord blood was collected post-delivery and pertussis toxin (PT)-IgG, filamentous hemagglutinin (FHA)-IgG and PT-neutralizing antibodies (PT-Nab) were assessed.

RESULTS: No adverse pregnancy, delivery, or neonatal outcomes attributed to aPgen TdaPgen or Td vaccination were reported. High anti-PT antibody levels were detected in cord samples from women vaccinated with aPgen (GMC PT-IgG 206.1 IU/mL, 95% CI 164.3‒258.6; GMT PT-Nab 105.3 IU/mL, 95% CI 81.7‒135.8) or TdaPgen (GMC PT-IgG 153.1 IU/mL, 95% CI 129.1‒181.5; GMT PT-Nab 81.5 IU/mL, 95% CI 66.4‒100.0). In the Td-only group, anti-PT antibodies were low (GMC PT-IgG 6.5 IU/mL, 95% CI 4.9‒8.8; GMT PT-Nab 3.8 IU/mL, 95% CI 2.8-5.1). The same was found for FHA-IgG. Recombinant pertussis vaccination at <27 or 27‒36 weeks gestation induced similar cord pertussis antibody levels.

CONCLUSION: This first real-world study confirms that recombinant pertussis vaccination in the 2nd or 3rd trimester of pregnancy results in high levels of passive immunity in infants.