Maternal Tdap and Influenza Vaccination Coverage Has Increased, But Gaps Remain

An infection with pertussis or influenza in a newborn can lead to serious and severe illness. However, vaccination against pertussis and the flu is not recommended until the ages of 2 months and 6 months, respectively.

In order to create protection against these diseases among newborns, pregnant women in the United States are advised to receive tetanus, toxoid reduced diphtheria toxoid, and acellular pertussis (Tdap) and influenza vaccines.

In spite of these recommendations, a survey conducted by the US Centers for Disease Control and Prevention in 2017-18 found that only 54.4% and 49.1% of pregnant women self-reported receiving the Tdap and influenza vaccinations, respectively.

Due to the fact that the survey data was made up of self-reported answers, which could be subject to recall, non-response or bias, a team of investigators set out to investigate maternal coverage of the 2 vaccines, using data from 2 large administrative claims databases.

Data for the retrospective cohort study, published in the American Journal of Preventive Medicine were taken from the MarketScan Commercial and Multi-State Medicaid Databases, from 2009-2017 and were analyzed by the study team in 2018.

The investigators included data from women between the ages of 15 and 44 years on the date of pregnancy but excluded pregnancies with a gestational age of less than 23 weeks from the Tdap vaccination endpoint due to the optimal recommended gestational age for Tdap vaccination. The study team used multivariable logistic regression models to identify predictors of vaccination.

According to the results, the Tdap vaccination subpopulation included 1,421,452 Commercial and 523,635 Medicaid pregnancies. On the other hand, the influenza vaccination subpopulation included 1,862,705 Commercial and 628,079 Medicaid pregnancies.

The investigators observed “marked increases” in coverage from 2010 to 2017: “from 1.0% to 56.3% (Commercial) and from 0.5% to 41.4% (Medicaid) for Tdap, and from 14.7% to 31.3% (Commercial) and from 9.7% to 17.5% (Medicaid) for influenza.”

When assessing data, the study team determined that the likelihood of Tdap/influenza vaccination increased significantly when the participants received other vaccines and had additional pregnancy-related health care visits.

While this study reports progress, the investigators urge that there is still more to be done.

“Although maternal Tdap and influenza vaccination coverage increased substantially from 2010-2017 among large, geographically diverse US cohorts, coverage remained suboptimal, potentially putting newborns at risk of pertussis and influenza,” the authors wrote in their conclusion.

When discussing strategies to increase the uptake of maternal vaccine coverage, the study authors say that efforts should target women who have been identified as having a reduced likelihood of receiving recommended vaccines. This population includes women who are younger, black, residing in rural areas, have multiple gestations, and have an inpatient admission for pregnancy.

Additional research should center around understanding the barriers to maternal immunization as well as exploring which interventions are most effective in increasing vaccination uptake, particularly among pregnant women with characteristics associated with lower likelihood of vaccination.