Risk factors for hospitalization and death due to COVID-19 during endemic Omicron circulation, a population-based...

Knowledge about risk factors for hospitalization and death due to COVID-19 during the Omicron period remains limited. To support recommendations about vaccination and antiviral treatment, we investigated the association between common risk factors and COVID-19 related hospitalization and death during the Omicron period.

Nationwide registry data on the Swedish adult population was compiled for the period June 10, 2022, to March 31, 2023. Frequency of hospitalization and death due to COVID-19 were analyzed. Individual data were stratified by age, vaccination status, Charlson Comorbidity Index, and specific comorbidities. Poisson regression was used to estimate incidence risk ratios of independent risk factors for hospitalization and death including age, sex, comorbidities, care dependency, and socioeconomic factors.

Among the more than 8.3 million individuals in the study cohort, 13,941 hospitalizations and 2309 deaths due to COVID-19 were recorded. Multivariable analysis revealed that high age was the strongest risk factors for both hospitalization and death. Advanced comorbidity was the second strongest risk factor for hospitalization, and care dependency was the second strongest risk factor for death. Among comorbidities, recent chemotherapy, immune deficiency, multiple sclerosis, and chronic kidney disease stage V were the strongest risk factors for hospitalization and death.

Also, in the current Omicron endemicity, advanced age remains the strongest risk factor for hospitalization and death due to COVID-19, accompanied by advanced comorbidity and care dependency. These findings can guide public health recommendations such as vaccination strategies and antiviral treatment guidelines, helping to protect those most at risk.