Tetanus, diphtheria, acellular pertussis (Tdap) vaccination during pregnancy decreases the risk of pertussis infection by 36% for infants during their first 6 months of life and should be recommended to pregnant women after 27 weeks gestation, according to a recent vaccine report published in The Pediatric Infectious Disease Journal.

There is limited evidence surrounding the effectiveness of Tdap vaccination on the reduction of infant pertussis in a real-world setting. This study aimed to determine the efficacy of prenatal vaccination against pertussis infection in infants using 2 healthcare claims database pregnancy cohorts (1 publicly insured, 1 privately insured).

The cohorts of mother-infant pairs were obtained from the Medicaid Analytic eXtract (MAX; 2010-2014) and IBM MarketScan (2011-2015) databases and were used to estimate the effectiveness of preventing pertussis in the first 6 months of life by comparing prenatal vaccination vs no vaccination. The results obtained from the databases were pooled.

Cox proportional hazards models were used to estimate hazard ratios and potential confounders were adjusted using inverse probability weights. The analysis also included the effect of preterm delivery on pertussis risk. 

Findings of the study revealed that 25.6% (114,067/445,638) of pregnant women in the MarketScan database and 4.8% (33,286/695,262) of pregnant women in the MAX database received the Tdap vaccine prior to delivery. Mothers of term infants were more likely to receive vaccination during pregnancy than mothers of preterm infants; only 21.2% and 3.8% of pregnancies with preterm delivery had been vaccinated in the MarketScan and MAX databases, respectively.

“The primary analysis comparing vaccination at any time during pregnancy with no vaccination estimated an adjusted HR of 0.74 (95% CI, 0.42–1.29) and 0.50 (95% CI, 0.24–1.04) in MarketScan and MAX, respectively,” the authors reported. They added, “The pooled hazard ratio for Tdap vaccination any time before delivery vs no vaccination was 0.64 [95% CI, 0.41–1.00].”

For mothers vaccinated prior to 37 weeks, the estimated hazard ratios were 0.11 (95% CI, 0.03-0.36) for preterm infants and 0.78 (95% CI, 0.48-1.29) for term infants. Additionally, findings of the study revealed a stronger protective hazard ratio during outbreaks of pertussis. 

“Our results support the effectiveness of the current recommendation of Tdap vaccination during pregnancy to prevent infant pertussis,” the authors concluded. They added, “Based on our findings, vaccinating early in the recommended 27–36-week window will provide the largest population benefit by increasing coverage of preterm infants, who benefit the most from this maternal vaccination.”

Disclosure: Some authors have declared affiliations with or received funding from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.


Mott K, Huybrechts KF, Glynn RJ, Mogún H, Hernández-Diaz S. Tetanus, diphtheria, acellular pertussis vaccination during pregnancy and risk of pertussis in the newborn in publicly and privately insured mother-infant pairs in the United States. Pediatr Infect Dis J. [Published online March 2, 2021.] doi: 10.1097/INF.0000000000003099