Barug D, et al. - Researchers investigated how maternal tetanus, diphtheria, and acellular pertussis (Tdap) vaccination influence the pertussis antibody responses of infants starting primary vaccinations at age 3 months in this open-label, parallel, randomised, controlled trial. At 36 midwife clinics in the Netherlands, 118 pregnant women were recruited through independent midwives to receive Tdap vaccination either at 30–32 weeks of pregnancy (maternal Tdap group) or within 48 h after delivery (control group). The maternal Tdap group included 58 pregnant women and the control group had 60 pregnant women. Infants in the maternal Tdap group showed higher geometric mean concentration (GMC) of pertussis toxin antibodies than the control group infants at age 3 months and also significantly higher compared with control infants at age 2 months. This supported a delay of the first pertussis vaccination in infants of maternal Tdap group until at least age 3 months. Antibody concentrations after primary and booster vaccinations were influenced by maternal antibody interference.