April 18, 2017
3 min read

Maternal Tdap vaccine reduced infant pertussis risk by 91% in first 2 months

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Children whose mothers received the tetanus-diphtheria-acellular pertussis vaccine during pregnancy exhibited a 91% reduced risk of pertussis within the first 2 months of life, according to new research published in Pediatrics.

Additionally, the researchers found that maternal Tdap vaccination did not interfere with infant diphtheria, tetanus and acellular pertussis (DTaP) vaccines but rather supplemented their protection.

Nicola P. Klein, MD, PhD
Nicola P. Klein

“The strategy of immunizing pregnant women to boost maternal antibody transfer appears to be more effective for protecting young infants against pertussis than are attempts at ‘cocooning,’ in which mothers and other persons in close contact with newborns are vaccinated,” Nicola P. Klein, MD, PhD, codirector of the Kaiser Permanente Vaccine Study Center, and colleagues wrote. “Substantial evidence supports the safety of Tdap vaccination in pregnancy. However, there is limited evidence on its effectiveness, and only one study has estimated Tdap vaccine effectiveness in infants who have also received the DTaP vaccine.”

For researchers to evaluate and estimate the effectiveness of maternal Tdap vaccination during pregnancy before the first infant dose of DTaP at 2 months and 1 year, infants born at Kaiser Permanente Northern California between 2010 and 2015 (n = 148,981) were included in a retrospective cohort study. Each additional dose of DTaP given to a child was accounted for.

According to study results, the effectiveness of maternal Tdap vaccination at preventing pertussis was 91.4% during the first 2 months of life. Within the first year of life, maternal vaccination was 69.0% effective.

Before an infant’s DTaP vaccination, maternal vaccine efficacy was observed at 87.9%. Effectiveness of vaccination against pertussis reached 81.4% after one dose of DTaP was administered to the child, 6.4% after two doses and 65.9% after three doses.

“We should be cautious about the interpretation of how much additional protection infants are provided by maternal Tdap vaccination in addition to DTaP vaccination between the second and third doses, because the CI is wide,” Klein and colleagues wrote. “However, it is reassuring that at every level of DTaP vaccine exposure, children whose mothers received the Tdap vaccine are better protected.” by Katherine Bortz

Disclosure: Drs. Baxter and Klein report potential conflicts of interest including the pertussis vaccines purchased by Kaiser Permanente Northern California, which are the focus of this study, were manufactured by GlaxoSmithKline and Sanofi Pasteur. The other authors have indicated they have no potential conflicts of interest.