Tetanus, diphtheria, and acellular pertussis vaccination during pregnancy and reduced risk of infant acute respiratory infections

•Clinicians recommend women receive Tdap vaccine at 27–36weeks of pregnancy for every pregnancy.•Among military mothers Tdap vaccination in pregnancy increased from 0.2% in 2006 to 32.3% in 2013.•Tdap vaccination at 27–36weeks of pregnancy was protective against infant acute respiratory infection.•Protection was also seen among mothers with prior vaccination, supporting repeat vaccination.•Of the 15 infants with pertussis, only 1 mother received Tdap vaccine in pregnancy (1st trimester). To protect infants from pertussis infection, the Advisory Committee on Immunization Practices (ACIP) recommends women receive the tetanus toxoid, reduced diphtheria toxoid, acellular pertussis (Tdap) vaccine between 27 and 36weeks of pregnancy. Here, we assessed the association between timing of maternal Tdap vaccination during pregnancy and acute respiratory infection (ARI) in infants