Effect of COVID-19 Vaccines on the Prevention and Severity of Omicron Strain in Liver Transplant Patient

Background: Because it is still not possible to accurately determine whether the injected vaccines affect the disease incidence and mortality or not in the newly diagnosed strains, the present study aimed to investigate the effect of injected Coronavirus disease 2019 (COVID-19) vaccines on the mortality rate among liver transplant patients infected with COVID-19 in Mashhad, Iran. Methods: This prospective cross-sectional study was conducted on liver transplant patients with moderate to severe COVID-19 referred to Montaseriyeh Hospital, Mashhad, Iran, from December 2021 to March 2022. The relationship between mortality due to Omicron strain was assessed with various variables. Results: In general, 97 liver transplant recipients were entered into the present study. Vaccine failure was reported in 43.5% of liver recipients. About 30% of the patients had not received any COVID-19 vaccination, and 2.9%, 40%, and 27.1% had received one, two, and three dosages of COVID-19 vaccination, respectively. Infection with COVID-19 was the cause of mortality in 11.3% of patients. No significant relationship was reported between mortality and the consumption of immunosuppressive agents (P > 0.05). Multiple linear regression showed that the number of received vaccine dosages was predictive of mortality due to infection with the Omicron variant in liver recipients (β = 0.13; P < 0.005). Conclusions: It was found that mortality due to COVID-19 vaccination was higher among the patients with fewer COVID-19 vaccination dosages and, consequently, could be related to vaccine-induced immunity in liver transplant recipients. However, due to the high vaccine failure rate, it seems that neutralizing antibody activity against Omicron variants is high.