Tdap Vaccine During Pregnancy May Protect Infants When Most Vulnerable

Newborns born to mothers who were given the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine during pregnancy received immunity from their mothers at birth in the first months of life, according to a new report in the Journal of the American Medical Association. The findings support current recommendations that women should receive the Tdap vaccine during the third trimester of pregnancy to protect newborns from pertussis.

Researchers at Baylor College of Medicine led by Flor Munoz, MD, began in 2009 and followed 48 pregnant women, 33 of whom were vaccinated in the third trimester of pregnancy, and 15 who were vaccinated postpartum. Thirty-two nonpregnant women were vaccinated as controls.

The study found that the Tdap vaccine was safe and effective in pregnant women, and that pregnant women had adequate immune responses from the vaccine, similar to the women who were not pregnant but received the vaccine.

At delivery, women who were vaccinated during pregnancy had significantly higher concentrations of antibodies to pertussis compared with women who received their vaccinations postpartum. The infants of mothers vaccinated during pregnancy had significantly higher concentrations of antibodies to pertussis at birth and during the first 2 months of life, probably giving them protection from pertussis during the most vulnerable period, when they are not yet vaccinated themselves.

“Maternal immunization with Tdap is the most effective method currently available to protect babies against pertussis,” Munoz said in a statement. “However, infants need to receive their recommended vaccines starting at 2 months of age, even if the mother receives the vaccination during pregnancy.”

The infants were also found to be able to respond to their own subsequent vaccinations for pertussis.