Incidence and predictors of clinical failure after early treatment for mild-to-moderate COVID-19 in high-risk individuals: A multicentric cohort study.

Objectives: To estimate the risk of COVID-19-related hospitalization and death (CovH/D), among high-risk individuals early treated for COVID-19 and to identify associated factors.

Methods and results: A multicenter cohort of 12,475 high-risk outpatients (female 50.2%, median age 70 years [IQR 57-80], fully vaccinated 79.1%, immunocompromised 23.2%) treated with monoclonal antibodies or antivirals for mild-to-moderate COVID-19 (March 2021-May 2023) in the Lazio region, Italy. The unadjusted risk of CovH/D by Day 30 was 3.08% (95% CI 2.7%-3.4%). By means of logistic regression models, which included a specific set of potential confounders for each exposure of interest, we observed a higher risk for the elderly, unvaccinated and immunocompromised participants. Using the "Delta period" as a reference, a decreased risk was observed for Omicron waves.

Conclusions: Despite the administration of COVID-19 early treatment and the decreasing risk of CovH/D across the calendar periods, the elderly, the unvaccinated and the immunocompromised people remain at high risk of clinical progression.