A comparative analysis of COVID-19 deaths during the alpha and delta to Omicron transition, from a forensic perspective in Greece

Abstract Background Autopsy is the method of choice for examining risk factors, concomitant diseases, and the evolution of pathology in COVID-19 decedents. The global transition from the Alpha and Delta variants (before December 2021) to the Omicron variant (after January 2022) raised questions about the demographic and pathologic characteristics of COVID-19-positive decedents who underwent autopsy. A comparative retrospective analysis, including forensic autopsy data, was conducted to categorize cases by the dominance of the Delta and Omicron variants. The main variables examined included data like age, sex, place of death, vaccinations performed, alcohol and tobacco use, toxicological examination results, other pathology, several COVID-19 complications (e.g., diffuse alveolar damage, acute respiratory distress syndrome, microthrombosis), and histological examination results. A statistical analysis was performed to assess the differences between the two respective groups. Results The deceased during the Omicron period were significantly older and had pre-existing cardiovascular conditions. The Omicron period was characterized by less fulminant respiratory pathology, as serious COVID-19-related complications (e.g., diffuse alveolar damage, microthrombosis) were less common than in the Delta period. Inpatient deaths were more common during the Omicron period. Other factors, such as alcohol and tobacco use, and different concomitant diseases, did not offer statistically significant results. Conclusions Older median age and a higher burden of cardiovascular disease are indicated by the mortality patterns described in the Omicron period. Further research focusing on virological and histopathological data may aid in examining the trajectory of the COVID-19 mortality.