Clinical course and outcomes of COVID-19 infection in liver transplant recipients: single-center cross-sectional study

Background. The novel coronavirus infection (COVID-19) pandemic has had a significant impact on all areas of health care system, including organ donation and transplantation. Despite this, there were no large Russian studies of COVID-19 course and outcomes in liver transplant recipients.The study purpose was to determine prevalence, clinical course, severity, outcomes of COVID-19, as well as to assess the safety and efficiency of vaccination for disease prevention in liver transplant recipients.Material and methods. 260 recipients (71% of all patients at risk of COVID-19 disease) who underwent liver transplantation at State Research Center – Burnasyan Federal Medical Biophysical Center from May 2010 to September 2021 were included in a single-center cross-sectional study. Data collection was performed during a telephone or face-to-face interview from September 6, 2021 to September 20, 2021. If patients were hospitalized with COVID-19, we also analyzed the results of laboratory and instrumental tests, other medical documentation.Results. By mid-September 2021, the incidence of COVID-19 after liver transplantation was 31% (75 cases in 260 recipients). Asymptomatic course was observed in 11 (15%) patients. Hospitalization was required in 18 (28%) cases. In one case, COVID-19 infection was the cause of death. Mortality and death rate in the study cohort were 1% (1/75) and 0.4% (1/260), respectively. Risk factors that statistically significantly increased the likelihood of infection with SARS-CoV-2 were contact with the patient (OR: 12.9; 95% CI: 6.6 - 25.0) and non-compliance with non-specific prophylaxis measures (OR: 2.0; 95 % CI: 1.1 - 3.7). The recipient's age of 60 years or more significantly increased the risk of severe infection (OR 5.0; 95% CI: 1.3 - 18.7). None of the immunosuppressive therapy regimens significantly increased the risk of severe disease. Tacrolimus monotherapy or in combination with other drugs reduced the risk of severe COVID-19 (OR: 0.2; 95% CI: 0.1 - 0.95). Vaccination against SARS-CoV-2, which was performed in 42 (17%) recipients, did not cause serious adverse events and significantly reduced the risk of COVID-19 disease (OR: 7.2; 95% CI: 1.7 - 31.3). The detection rate of specific IgG antibodies to SARS-CoV-2 was 94% in recipients who had undergone the disease and 45% among those vaccinated (p<0.001). The achieved level of herd immunity against COVID-19 in the analyzed cohort was 48%. Conclusion. Adult liver transplant recipients are not at an excessive risk of COVID-19 disease. Compliance with preventive measures and vaccination can significantly reduce the risks of infection and severe infection. There is no objective evidence that immunosuppressive therapy increases the risk of severe COVID-19 in liver transplant recipients. In the context of the ongoing COVID-19 pandemic, tacrolimus monotherapy may be considered as a safe regimen of maintenance immunosuppression.