Maternal Immunization With Tetanus Toxoid, Reduced Diphtheria Toxoid, Reduced-dose (2 µg) Recombinant Pertussis Vaccine (TdaP2gen) and Its Effect on the Immune Response in Thai Infants up to 15-18 Months Old

Pertussis remains a major global public health problem. In Thailand, pertussis vaccination is recommended during pregnancy at 20-32 weeks' gestation, together with routine childhood diphtheria-tetanus-pertussis vaccination administered as a primary series at 2, 4, and 6 months and booster doses at 18 months and 4-6 years of age. TdaP2gen, a newly developed combined tetanus, diphtheria, and recombinant genetically detoxified acellular pertussis vaccine containing 2 µg pertussis antigen, has shown favorable safety and non-inferior immunogenicity compared with existing pertussis vaccines. However, data on its use in pregnant women, transplacental antibody transfer, and potential immune interference in infants remain limited. This study aims to evaluate the safety and immunogenicity of TdaP2gen in pregnant women, assess antibody transfer to newborns, and investigate immune responses to tetanus, diphtheria, and pertussis following primary and booster pertussis-containing vaccinations in infants and toddlers, including comparisons between whole-cell and acellular pertussis-containing vaccine schedules.