Rates of and Factors Associated With Primary and Booster COVID-19 Vaccine Receipt by US Veterans, December 2020 to June 2022

IMPORTANCE COVID-19 vaccination rates remain suboptimal in the US. Identifying factors associated with vaccination can highlight existing gaps and guide targeted interventions to improve vaccination access and uptake. OBJECTIVE To describe incidence and patient characteristics associated with primary, first booster, and second booster COVID-19 vaccination in the Veterans Health Administration (VHA). DESIGN, SETTING, AND PARTICIPANTS This retrospective cohort study assessed US veterans receiving care in VHA medical centers and outpatient clinics as of December 1, 2020. All VHA enrollees with an inpatient, outpatient, or telehealth encounter in VHA as well as a primary care physician appointment in the preceding 24 months were included. EXPOSURES Demographic characteristics, place of residence, prior SARS-CoV-2 infection, and underlying medical conditions. MAIN OUTCOMES AND MEASURES Cumulative incidence of primary, first booster, and second booster COVID-19 vaccination through June 2022. Cox proportional hazards regression was used to identify factors independently associated with COVID-19 vaccination. RESULTS Among 5632413 veterans included in the study, 5094392 (90.4%) were male, the median (IQR) age was 66 (51-74) years, 1032334 (18.3%) were Black, 448714 (8.0%) were Hispanic, and 4202173 (74.6%) were White. Through June 2022, cumulative incidences were 69.0% for primary vaccination, 42.9% for first booster, and 9.3% for second booster. Cumulative incidence for primary vaccination increased with increasing age, from 46.9% (95% CI, 46.8%-47.0%) among veterans aged 18 to 49 years to 82.9% (95% CI, 82.8%-83.0%) among veterans aged 80 to 84 years. More Black veterans completed primary vaccination (71.7%; 95% CI, 71.6%-71.8%) compared with White veterans (68.9%; 95% CI, 68.9%-69.0%), and more urban-dwelling veterans completed primary vaccination (70.9%; 95% CI, 70.9%-71.0%) compared with highly rural-dwelling veterans (63.8%; 95% CI, 63.4%-64.1%). Factors independently associated with higher likelihood of both primary and booster vaccination included older age, female sex, Asian or Black race, Hispanic ethnicity, urban residence, and lack of prior SARS-CoV-2 infection. CONCLUSIONS AND RELEVANCE In this cohort study of US veterans, COVID-19 vaccination coverage through June 2022 was suboptimal. Primary vaccination can be improved among younger, rural-dwelling veterans. Greater uptake of booster vaccination among all veterans is needed.