Effect of SARS-CoV-2 Vaccination in Liver Transplant Recipients

Inclusion Criteria: * Liver transplanted patients \>18 years of age. * Patients who underwent liver transplantation between 01/2015 to 12/2021. * Patients who underwent liver transplantation at "Policlinico Tor Vergata, Rome, Italy". * Patients who have had three doses of a vaccine for the prevention of COVID-19. * Patients who have had three doses of a SARS-CoV-2 vaccine and who have contracted SARS-CoV-2 infection. Exclusion Criteria: * Patients who have more or less than three dose of a vaccine for the prevention of COVID-19 * Patients not vaccinated for prevention of SARS-CoV-2 infection. * Patients who have had three doses of a vaccine for the prevention of COVID-19 prior to liver transplantation.