The COVID-19 Hospitalization Metric in the Pre- and Post-vaccination Eras as a Measure of Pandemic Severity: A Retrospective, Nationwide Cohort Study

“Setting: Multi-center, nationwide study conducted in the healthcare system of the US Department of Veterans Affairs (VA) from March 1, 2020, through June 30, 2021…

Exposure: SARS-CoV-2 vaccination status at the time of hospitalization. Patients were regarded as fully vaccinated starting 14 days after receiving the second of a 2-dose regimen or 14 days after receipt of a single-dose vaccine.

Results: … Among 15,196 admissions on or after 1/21/2021 (unvaccinated, 11,569; vaccinated, 3,627), 7,908 met the case definition for moderate-to-severe disease (unvaccinated, 6,362; vaccinated, 1,546).”