US Maternal Tdap and Influenza Immunization Rate Is Suboptimal

Pregnant Woman being vaccinated
Pregnant Woman being vaccinated

Maternal coverage with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) and influenza vaccinations between 2010 and 2017 remained suboptimal among large, geographically diverse cohorts in the United States. This is according to data published in the American Journal of Preventative Medicine.

The data for this retrospective cohort study were extracted from the MarketScan Commercial and Multi-State Medicaid administrative claims databases. Women aged 15 to 44 years at the time of pregnancy end were included, while pregnancies with a gestational age less than 23 weeks were excluded from the Tdap vaccination endpoint.

The subpopulations of Tdap and influenza vaccinations included 1,421,452 women in the MarketScan Commercial database and 523,635 women in the Medicaid database and 1,862,705 women in the MarketScan database and 628,079 in the Medicaid database, respectively. Marked increases in vaccination coverage for both Tdap and influenza were observed between 2010 and 2017. Results demonstrated an increase from 1.0% to 56.3% (MarketScan) and from 0.5% to 31.4% (Medicaid) for Tdap, and from 14.7% to 31.3% (MarketScan) and from 9.7% to 17.5% (Medicaid) for influenza. The likelihood of vaccination with either Tdap or the influenza vaccine increased significantly with the receipt of the other and with more pregnancy-related health care visits.

Results also identified 2 statistically significant factors related to the likelihood of vaccination rates: rates increased with the receipt of other vaccines during pregnancy (odds ratio, 3.39-5.19) and decreased with no pregnancy-related clinic visits (odds ratio, 0.23-.040).

Study limitations for this work included potential data coding and entry errors in claims and a lack of generalizability to uninsured, self-insured, or intermittently insured women. Further, researchers acknowledged that claims databases may not capture vaccinations administered in free clinics or those eligible under the Vaccines for Children program.

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According to investigators, while vaccination coverage increased during the study period, the rates of coverage are still suboptimal. They recommended, “strategies to increase maternal vaccination coverage could be targeted toward pregnant women identified to have a reduced likelihood of vaccination: those who are younger, black, residing in rural areas, with multiple gestation, and a pre-pregnancy inpatient admission.” Future studies aimed at understanding barriers to maternal immunization and the design of interventions were also warranted according to the study’s authors.


Ghaswalla P, Poirrier JM, Packnett ER, Irwin DE, Gray SR, Buck PO. Maternal immunization in the U.S.: a nationwide retrospective cohort study. Am J Prev Med. 2019;57:e87-e93.