Issue: November 2017
November 21, 2017
3 min read

Tdap vaccinations in pregnant women jump more than 50%

Issue: November 2017
You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

The rate of pregnant women receiving a tetanus, diphtheria and pertussis vaccine increased dramatically in numerous metropolitan areas of the United States — by more than 50% over several years — according to a recent report. The increase in immunization stems from recommendations from the Advisory Committee on Immunization Practices, researchers said.

Tdap vaccinations among pregnant women increased from less than 1% before 2009 to 54% in 2015, they wrote in an MMWR.

“These increases reflect the implementation of evolving recommendations, which currently recommend that all pregnant women be vaccinated during each pregnancy, ideally in the third trimester,” Stephen Kerr, MPH, an epidemiologist at Boston University’s Slone Epidemiology Center, and colleagues wrote.

Positive findings

Kerr and colleagues assessed data on vaccinations of 5,606 infants’ mothers between 2006 and 2015. They included data from hospitals in the Philadelphia and San Diego areas, as well as statewide registries in New York and Massachusetts.

Nancy Messonnier

ACIP recommendations on Tdap vaccination progressed throughout the study period. In 2006, the group recommended postpartum immunization, adding that the vaccine could also be given during pregnancy.

In June 2011, the ACIP revised the timing of immunization, saying that previously unvaccinated pregnant women should receive the vaccine after 20 weeks’ gestation. And in October 2012, the group adopted its current recommendation.

The initial rate of Tdap vaccination rose to 9% in 2012, then to 28% in 2013 and 54% in 2015, Kerr and colleagues said. The proportion of women receiving Tdap in the third trimester increased from 94% in 2010 to 100% in 2015. Nearly all Tdap vaccinations — 96% — were administered in a traditional health care setting such as a primary care, obstetrics or prenatal clinic.

The proportion of women receiving Tdap in the third trimester increased from 94% in 2010 to 100% in 2015. The researchers touted the efficacy of vaccination in that trimester.

“A recent U.S. study found the Tdap vaccination during the third trimester of pregnancy was 85% more effective than postpartum vaccination at preventing pertussis in infants aged younger than 2 months,” they wrote.

They added that health care providers and patients alike can find resources at

Despite the large vaccination rate increases, the researchers warned that the prevalence of Tdap vaccination remains far below the ACIP recommendation that every woman be vaccinated during each pregnancy.

“Increasing vaccination coverage during pregnancy could help reduce the impact of pertussis on infant morbidity and mortality,” they wrote.

Maternal Tdap effective

New research suggests that administering Tdap vaccine to pregnant women during the third trimester is approximately 78% effective at preventing pertussis in newborns during their first 2 months, according to state and federal researchers.


In a case-control study, the researchers evaluated pertussis cases and maternal vaccination in newborns aged younger than 2 months with cough onset from 2011 through 2014 in six states, with controls matched by hospital and selected by birth certificate. The evaluation included 240 cases of pertussis and 535 control infants, 136 case mothers and 358 control mothers who had at least one valid Tdap dose 14 or more days before delivery. Seventeen case mothers and 90 control mothers received Tdap during the third trimester.

The researchers estimated the overall vaccine effectiveness against pertussis when Tdap is given in the third trimester to be 77.7% (95% CI, 48.3%-90.4%), increasing to 78.4% (95% CI, 49.8%-90.7%) when vaccination is performed in the recommended window of 27 to 36 weeks’ gestation. The vaccine’s effectiveness against pertussis is 64.3% (95% CI, –13.8% to 88.8%) when given during the first or second trimester and 50.8% (95% CI, 2.1%-75.2%) when given at any time before pregnancy, including 83% (95% CI, 49.6%-94.3%) when given within 2 years before pregnancy, according to the researchers.

They estimated Tdap’s effectiveness to prevent hospitalization to be 90.5% (95% CI, 65.2%-97.4%). According to the CDC, infants aged younger than 1 year are at the highest risk for severe complications or death from pertussis, which typically kills between five and 15 babies each year, most in the 2 months before they can receive their own vaccination.

“Women have such a great opportunity to help protect their babies before they enter the world by getting Tdap vaccine while pregnant,” Nancy Messonnier, MD, director of CDC’s National Center for Immunization and Respiratory Diseases, said in a news release. “This study highlights how babies can benefit when their mothers get the vaccine and reinforces CDC’s recommendation for women to get Tdap vaccine in the third trimester of each pregnancy.” – by Joe Green and Gerard Gallagher

Disclosures: Kerr and Messonnier report no relevant financial disclosures. Please see the studies for all other authors’ relevant financial disclosures.