Background: The highly transmissible nature of the Omicron variant raises concerns globally.

Objective: To investigated the clinical characteristics and severity of COVID-19 patients infected with the Omicron variant in Thailand, comparing it to the previously dominant Alpha and Delta variants.

Materials and Methods: Retrospective data from two secondary hospitals in Thailand during the Omicron variant’s prevalence were analyzed. Demographic and clinical information, including age, comorbidities, symptoms, lab results, and outcomes, were compared with the Alpha and Delta variants. Severity was assessed based on the presence of pneumonia and mortality.

Results: Preliminary findings revealed distinct clinical characteristics in COVID-19 patients with the Omicron variant compared to the Alpha and Delta variants. Common symptoms like fever, cough, sore throat, and fatigue varied in frequency and severity across the variants. Breakthrough infections were more prevalent with the Omicron variant. Differences in the development of pneumonia were observed.

Conclusion: This comparative study provides initial insights into the clinical characteristics and severity of COVID-19 patients with the Omicron variant in Thailand. Further research is required to validate these findings and improve understanding of Omicron’s impact on disease outcomes. This knowledge will inform effective strategies to mitigate the spread and severity of COVID-19 caused by the Omicron variant.

Keywords: Omicron variant; Clinical characteristics; Severity; COVID-19; Delta variant; Alpha variant

DOI: 10.35755/jmedassocthai.2023.06.13857

Received 11 April 2023 | Revised 14 May 2023 | Accepted 31 May 2023