Halperin SA, et al. - Considering the protection afforded by immunization of pregnant women with tetanus-diphtheria-acellular pertussis vaccine (Tdap) against pertussis to the newborn infant, researchers measured the safety and immunogenicity of Tdap during pregnancy and the impact on the infant’s immune response to primary vaccination at 2, 4, and 6 months and a booster vaccination at 12 months of age. In this randomized, controlled, observer-blind, multicenter clinical trial, Tdap or tetanus-diphtheria (Td) vaccine was administered to a total of 273 women in the third trimester who subsequently provided information for the safety analysis and samples for the immunogenicity analyses; serum for the immunogenicity analyses was obtained from 261 infants. As per outcomes, immunization of pregnant women with Tdap led to higher levels of antibodies early in infancy, but lower levels after the primary vaccine series. Both groups had similar rates of adverse events.