Introduction. Vaccine mandates have been used to minimize the duty days lost and deaths attributable to infectious disease among active duty Service members (ADSMs). In response to the global COVID-19 pandemic, in August 2021, the United States Department of Defense issued a COVID-19 vaccine mandate for all ADSMs. This study aimed to investigate COVID-19 vaccine uptake among the ADSM population, as well as factors associated with timing of COVID-19 vaccine receipt. Methods: This study included ADSMs on active duty between 1/1/2020-6/30/2022. Univariate analyses investigated associations between demographic factors (age, sex, race, ethnicity, branch of service, rank, state of residence) and COVID-19 diagnosis with the following outcomes: 1) time to primary series initiation in relation to the DoD vaccine mandate, 2) time between doses of the two-dose primary series, and 3) time between booster eligibility and receipt. Results: A total of 1,799,466 ADSMs were included, with 90% receiving ≥1 COVID-19 vaccine dose during the study period and 77% initiating the primary series prior to the mandate. Over 80% of ADSMs received a complete primary series, with 96% of those adhering to the recommended regimen. History of COVID-19 diagnosis was associated with later receipt of all doses. Conclusions: COVID-19 vaccine uptake was high among all ADSMs, with the majority initiating the primary series before the mandate. The high vaccine uptake among ADSMs shown here may be used as a guide to both military and civilian pandemic policy and outreach efforts related to enhanced vaccine uptake.

The authors have declared no competing interest.

Support for this work was provided by the Infectious Disease Clinical Research Program (IDCRP), a Department of Defense program executed through the Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biostatistics through a cooperative agreement with The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF). This project has been funded by the National Institute of Allergy and Infectious Diseases, National Institutes of Health, under Inter-Agency Agreement Y1-AI-5072, and the Defense Health Program, U.S. DoD, under award HU0001190002.

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