Evaluation of clinical characteristics in hospitalized COVID-19 patients across different waves

BACKGROUND: Since its initial spread in 2020, there have been several surges in new COVID-19 cases following by declines (waves) across the globe, driven by different SARS-CoV-2 variants. We investigated clinical characteristics between COVID-19 patients hospitalized during two different waves, and their relationship with clinical outcomes. METHODS: We retrospectively collected a wide range of clinical characteristics in COVID-19 patients who were hospitalized between October 2020 and January 2021 (group A, unvaccinated, N.=182) and between December 2021 and April 2022 (group B, vaccinated, N.=160). The primary endpoint was in-hospital death (non-survivors) vs. discharge or transfer to another ward (survivors). RESULTS: Patients in group B were significantly older, were more frequently females, had a lower Body Mass Index and a higher Charlson Comorbidity Index, and received overall less intensive treatment compared to group A. There were no significant between-group differences in mortality. In both groups, mortality was independently associated with age and intensity of care received. However, an independent association between comorbidity status and mortality was observed only in group A. CONCLUSIONS: Despite being older and having a higher comorbidity burden, group B received less intensive treatment and had similar in-hospital mortality to group A. This might reflect vaccine uptake and/or less severe SARS-CoV-2 variants in later COVID-19 waves. Further research is required to address whether this trend is maintained in future COVID-19 waves.