Potential impact of parental Tdap immunization on infant pertussis hospitalizations.

We estimated the potential impact of parental Tdap immunization before delivery, at delivery and at the 2-week newborn visit on U.S. infant pertussis hospitalizations. We used published data for pertussis hospitalization rates among U.S. infants aged 0-4 months, the Tdap vaccine efficacy in adults, and the proportion of infants with pertussis <6 months of age in which either parent was the source (16-40% from mothers and 16-20% from fathers). Immunizing parents before pregnancy or ≥ 2 weeks prior to delivery should reduce pertussis hospitalizations among infants 0-4 months by 2694-9314 if both parents are vaccinated, and by 1347-6909 if only mothers are vaccinated. Greater reductions in pertussis hospitalizations would be achieved if parents are immunized ≥ 2 weeks prior to delivery than after delivery or the 2-week newborn visit. Although immunizing parents prior to pregnancy or delivery is best, immunizing parents in the postpartum period should provide protection to that newborn and to infants of subsequent pregnancies.