Unvaccinated Non-Elderly Adult Population Hospitalized for COVID-19: Risk for Severe Disease and Poor Outcomes

Abstract

Introduction: Vaccination offers significant protection against hospitalization and death due to severe COVID-19. However, a significant portion of the nonelderly U.S. adult population remains unvaccinated. Methods: This retrospective analysis of adult patients aged under 65 years hospitalized with PCR-confirmed SARS-CoV-2 between March and November 2021 assessed the age-biased risk for severe disease and outcome in non-elderly unvaccinated adults hospitalized for COVID-19. Main measures included predisposing risk factors, disease severity and progression, and outcomes in non-elderly adults compared between (1) vaccinated and unvaccinated individuals and (2) unvaccinated individuals grouped by 10-year age increment. Results: Two hundred nineteen non-elderly adults were included; of whom, 82.6% were unvaccinated. Overall, unvaccinated patients were more likely to be obese (60% vs 29%, P <46 years, unvaccinated patients aged ≥46 years demonstrated 1.47- and 3.49-times higher likelihood of oxygen dependency upon discharge (P =.002) and requiring higher level of care or worse at discharge (P =.004), respectively. Conclusion: Results from our non-elderly cohort affirm the benefit of vaccination despite a subset requiring hospitalization for breakthrough infection. In unvaccinated non-elderly adults, risk for worse outcomes and severe disease increased substantially from middle age onward and provides strong support for vaccination efforts in this population.