Coverage and effectiveness of mRNA SARS-CoV-2 vaccines among United States Veterans

Abstract Importance The scope of vaccination rollout and effectiveness of mRNA SARS-CoV-2 vaccines in the United States (US), and US Veterans specifically, has not been fully assessed. Objective To estimate receipt of SARS-CoV-2 vaccines, and vaccine effectiveness (VE) against SARS-CoV-2 infection, subsequent disease-related severity and mortality. Design, Setting, and Participants First, receipt of any SARS-CoV-2 vaccine by March 7, 2021 was described for all enrolled and alive Veterans within the Veterans Health Administration (VHA). Second, to evaluate mRNA SARS-CoV-2 VE, a matched test negative case-control evaluation was conducted across all VHA facilities utilizing SARS-CoV-2 positive (cases [n=16,690]) and negative (controls [n=61,610]) tests from Veterans aged ≥18 years old who routinely sought care at a VHA facility and were tested for SARS-CoV-2 from December 14, 2020, through March 14, 2021. Exposures Vaccination histories were obtained from pharmacy and medical records to determine if patients were unvaccinated, partially vaccinated (from 7 days after first dose until day of second dose of mRNA SARS-CoV-2 vaccine), or fully vaccinated (from 7 days after second dose of mRNA SARS-CoV-2 vaccine) at time of SARS-CoV-2 test. Main Outcome Measures Primary outcomes were (1) vaccine receipt among Veterans and specific subpopulations, (2) VE calculated from odds ratios (ORs) with 95% confidence intervals (95% CI) for the association between SARS-CoV-2 infection and full vs. no vaccination, and (3) VE against infection for partial vs. no vaccination. VE against COVID-19-related hospitalization and death were also estimated. Results By March 7, 2020, among 6,170,750 Veterans, 1,547,045 (23.1%) received at least one SARS-CoV-2 vaccine. Based on the analysis of mRNA SARS-CoV-2 vaccines, VE against infection was 93.7% (95% CI 92.0-95.0) and 57.7% (95% CI 53.5-61.5) for full and partial vaccination (vs. no vaccination), respectively. VE was similar for subpopulations. VE against COVID-19-related hospitalization and death for full vs. no vaccination was 90.7% (95% CI 90.0-91.3) and 94.7% (95% CI 91.3-98.1), respectively. Conclusion and Relevance Vaccines are effective in reducing SARS-CoV-2 infections and disease-related severity and mortality in the Veteran population. Effective vaccine, as well as their efficient and equitable distribution, are important for reducing COVID-19 disease burden among Veterans. Key Points Question What is the scope of VHA vaccination rollout and the impact of mRNA SARS-CoV-2 vaccination among Veterans? Findings Vaccination rollout reached all Veteran subpopulations in the first three months. Effectiveness of full vaccination with mRNA SARS-CoV-2 vaccines was 93.7% for preventing infection, comparable to that demonstrated in clinical trials. Effectiveness was similarly high for the elderly, ethnic and racial minorities, individuals with low income, homeless persons, and immunocompromised Veterans. Meaning Effective vaccines and their efficient and equitable distribution helped the VHA to reduce COVID-19 disease burden and disparities among Veterans within the first three months of vaccine distribution.