In a recent study posted to the medRxiv* preprint server, researchers in Sweden investigated coronavirus disease 2019 (COVID-19) severity among unvaccinated adults during the periods of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant of concern (VOC) dominance compared to the severity of pre-Omicron VOC infections.

The health burden of SARS-CoV-2 infections among Western nations reduced in 2022, attributed to COVID-19 vaccinations and Omicron VOC predominance. However, a sizeable proportion of individuals continue to be unvaccinated, among whom COVID-19 severity during the Omicron wave is not thoroughly characterized.