Risk Factors Related to COVID-19 Reinfection and Fatality During the Omicron (BA.1/BA. 2) Period in Korea

Background: This study aimed to investigate the deaths due to coronavirus disease 2019 (COVID-19) reinfection and related risk factors. Methods: National cohort data were collected for a six-month period when omicron BA.1/ BA.2 variant was dominant in South Korea. Results: The long-term care facility residents (adjusted odds ratio, 3.11; 95% confidence interval [CI], 2.98-3.25) had significantly higher risk of reinfection than the general population. The risk of reinfection was significantly lower for persons with 2 or more vaccine doses compared to the unvaccinated. The risk of death was significantly higher in the reinfection group than in the primary infection group for persons in the 60-74 years age group (adjusted relative risk [aRR], 1.62; 95% CI, 1.19-2.20), and immunocompromised group (aRR, 4.56; 95% CI, 2.34-8.90). Conclusion: In these data, vaccination history was significantly related to reduced COVID-19 reinfection and severe progression, and scheduled vaccinations were important even with a history of infection.