Decreased Long‐term SARS‐CoV‐2‐Specific Humoral Immunity in Liver Transplant Recipients 12‐Months after COVID‐19

Long-term humoral immunity and its protective role in liver transplant patients has not been elucidated. We performed a prospective multicenter study to assess the persistence of IgG antibodies in liver transplant recipients 12 months after coronavirus disease 2019 (COVID-19). A total of 65 liver transplant recipients were matched with 65 non-transplanted patients by a propensity score including variables with recognized impact on COVID-19. Liver transplant recipients showed a lower prevalence of anti-nucleocapsid (27.7% vs. 49.2%, P = 0.02) and anti-spike IgG antibodies (88.2% vs. 100.0%, P = 0.02) at 12 months. Lower index values of anti-nucleocapsid IgG antibodies were also observed in transplant patients one year after COVID-19 (0.49 [IQR 0.15-1.40] vs. 1.36 [IQR 0.53-2.91], P < 0.001). Vaccinated liver transplant recipients showed higher antibody levels compared to unvaccinated patients (P < 0.001); antibody levels reached after vaccination were comparable to those observed in non-transplanted individuals (P = 0.70). In liver transplant patients, a longer interval since transplantation (OR=1.10, 95% CI 1.01-1.20) was independently associated with persistence of anti-nucleocapsid IgG antibodies one-year postinfection. In conclusion, compared with non-transplanted patients, liver transplant recipients show a lower long-term persistence of anti-SARS-CoV-2 antibodies. However, SARS-CoV-2 vaccination after COVID-19 in liver transplant patients achieves a significant increase in antibody levels, comparable to that of non-transplanted patients.