Infants born to mothers who received the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine during pregnancy are less likely to contract pertussis (whooping cough), develop complications, and die of the disease than those without such protection, a report today from the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP) suggests.
CIDRAP’s Vaccine Integrity Project (VIP), in conjunction with the nonprofit Evidence Foundation, released findings from the rapid systematic review and meta-analysis of peer-reviewed evidence today to add updated evidence to previous reviews of vaccine effectiveness (VE) and safety.
The analysis screened more than 14,000 papers and included 91 of them (29 from previous systematic reviews plus 62 new studies published from May 2016 to March 2026). Most studies (79) were observational, and 12 were randomized controlled trials.
In 2012, the Centers for Disease Control and Prevention’s (CDC’s) Advisory Committee on Immunization Practices (ACIP) recommended that women receive Tdap during every pregnancy in 2012. The vaccine is recommended during the third trimester, at 27 to 36 weeks’ gestation, to optimize antibody transfer to the baby.
The Tdap vaccine is a powerful tool that provides passive protection to infants from birth until they can begin the childhood diphtheria, tetanus, and acellular pertussis (DTaP) vaccine series beginning at 2 months of age, the report authors said.
But despite the introduction of pertussis vaccination in the United States in the 1940s, the disease remains endemic in the country, and most severe cases and deaths occur in infants younger than 3 months. “During the COVID-19 pandemic, rates of pertussis declined in the US,” the authors noted. “However, rates of pertussis infections have now returned to and in some areas now exceed pre-pandemic levels.”
In 2025, the CDC reported that 41% of infant pertussis patients younger than 6 months needed hospitalization, and 10 died.
Lower odds of infant hospital stays, ED visits
The combined estimate from 13 observational studies with more than 2 million participants on infant infection suggested a lower risk of pertussis in the infants of mothers who received Tdap during pregnancy relative to those of unvaccinated mothers (relative risk [RR], 0.27).
The combined estimate from seven observational studies on serious infant complications with more than 1 million participants suggested a decreased risk of pertussis-related hospitalization and emergency department (ED) visits among infants exposed to Tdap during pregnancy compared with those who were not (RR, 0.32).
