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.