In The News: Study: Maternal Pertussis Vaccination Prevents Most Infant Infections

From an Australian study, Healio reports maternal pertussis vaccination prevented 66% of pertussis infections among infants aged up to six months, with protection extending to eight months. No evidence was found the maternal vaccination blunted further vaccination response. CDC, WHO and UNICEF researchers disclosed last year that 25 million children worldwide were either unvaccinated or had incomplete vaccination of the Tdap series.

The study was initiated following the death of a five-week-old in the western part of the country. This led Australian researchers to note a nationwide pertussis increase in cases. A program was then launched to prevent severe infections that would replace an ineffective “cocooning” strategy of giving Tdap vaccinations to immediate family members.

Study researchers collected data on 279,418 infants born to 252,444 mothers across three Australian jurisdictions. Of the latter, 51% received the maternal pertussis vaccine and most of those occurring between 28 to 31 weeks gestation. Efficacy declined from 70.4.% among infants younger than two months to 43.3% in infants seven to eight months, and not significant thereafter.

Maternal pertussis vaccination might lower, according to the findings, the effectiveness of an infant’s third Tdap shot. However, the researchers say they did not observe higher rates of pertussis infection through 18 months. They hope the study will encourage more proactive approaches to the vaccination.

PIDS member Kathryn Edwards supplied an accompanying commentary. She said, “As with the Australian data, the U.S. data support the overall benefit of the maternal Tdap program and as with the Australian data do not suggest that blunting has led to an increase in cases within the first year of life. Despite these encouraging data demonstrating the important role of maternal immunization in reducing pertussis disease, Tdap immunization rates during pregnancy in Australia, the United Kingdom, and the United States remain between 50% and 60%. Active engagement to increase these rates should be implemented.”