Patterns and Predictors of COVID-19 Vaccine Uptake Among U.S. Active Duty Service Members, 2020-2022: Implications for Future Pandemics

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 U.S. DoD 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. Materials and Methods: This study included ADSMs on active duty between January 1, 2020, and June 30, 2022. Univariate analyses investigated associations between demographic factors (age, sex, race, ethnicity, branch of service, rank, and 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 2-dose primary series, and (3) time between booster eligibility and receipt. This research received an exempt determination by the USU Human Research Protection Program. Results: In total, 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. The history of COVID-19 diagnosis was associated with the 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.