Introduction: While COVID-19 poses a significant threat to immunocompromised patients, there is limited data on the clinical course and the risk factors for severe disease in the Korean transplant population. We have performed a single-center, cross-sectional, survey-based study to evaluate the clinical presentation, treatments, and outcomes of COVID-19 infection among renal transplant recipients (RTRs). 
Method: Eligible patients were adult RTRs who had reported confirmed COVID-19 infection. We conducted an electronic survey using a structured questionnaire via Google Forms to collect information on symptoms and treatments sought during the infection. The data were combined with data documented in the electronic health report. 
Result: Among 2,250 adult RTRs, 239(10.6%) patients had experienced COVID-19 infection. Patients had a mean age of 49 years, 56.9% (n=136) were male, and 77.1% (n=182) had received transplantation from a living donor.  217(90.7%), 215(89.9%), and 185(77.4%) patients had experienced COVID-19 infection after one, two, and three doses of vaccination, respectively. The mean period between the prior vaccination and infection was 84 days. The most common route of infection was family (n=100, 42%) followed by unknown and multi-use facilities. The main symptoms were cough (n=158, 66.1%), sore throat (n=145, 60.7), and fever (n=129, 54.0%). The majority of the patients were infected during the Omicron surge (n= 221, 92.4%) and initially received home treatment with URI medications (n=181, 75.7%) only. 14 patients experienced severe disease (WHO severity scale), and there were (0.8%) mortalities. Comparing Delta vs. Omicron there was a difference in antiviral therapy (X²=10.552, p=.001), only URI medication (X²=6.868, p=.009) vaccination times (X²=17.026, p=.001), aggravation Symptom after confirmed 5days (X²=7.406, p=.006), severity (X²=16.763, p=<.001) and hospitalization (X²=44.073, p=<.001). Factors independently associated with pneumonia were old age (OR 1.06), vaccination (OR 6.43) Wuhan, or Delta vs omicron (OR 4.55) in the multivariate logistic model.
Conclusion: The mortality rate associated with COVID-19 disease was higher in kidney transplantation patients. Effective prevention and management are important in high-risk groups, such as immunosuppressed patients. larger studies are warranted to confirm these findings.