Vaccination during pregnancy and modulation of IgG response to pertussis vaccines in infants: The impact of different vaccine formulations.

The IgG response following infant diphtheria-tetanus-acellular pertussis (DTaP) immunization is influenced by the formulation of the infant and/or the adult vaccine (Tdap) given during pregnancy. DTaP vaccines containing either 3 (DTaP3) or 5 (DTaP5) pertussis antigens are commonly used. By conducting a secondary analysis of a large randomized controlled trial, we compared IgG levels against pertussis vaccine antigens in children of Td- and Tdap5-vaccinated mothers, after stratifying by infant vaccine formulation. After immunization with a primary series of DTaP5, but not DTaP3, IgG GMCs against pertussis antigens were significantly lower in infants of Tdap-immunized mothers compared with infants of Td-vaccinated mothers (pertussis toxin: GMC = 52.3[Tdap5] vs 83.5[Td], p < 0.001). Before and after the DTaP booster dose, IgG GMCs were similar in infants of Tdap- and Td-immunized mothers specifically when infants received the DTaP3 vaccine. The combination of the TdaP5 vaccine for mothers and the DTaP3 vaccine for children could attenuate Tdap-associated immunomodulation.