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Decreased Long‐Term Severe Acute Respiratory Syndrome Coronavirus 2–Specific Humoral Immunity in Liver Transplantation Recipients 12 Months After Coronavirus Disease 2019

Long‐term humoral immunity and its protective role in liver transplantation (LT) patients have not been elucidated. We performed a prospective multicenter study to assess the persistence of immunoglobulin G (IgG) antibodies in LT recipients 12 months after coronavirus disease 2019 (COVID‐19). A total of 65 LT recipients were matched with 65 nontransplanted patients by a propensity score including variables with recognized impact on COVID‐19. LT recipients showed a lower prevalence of anti‐nucleocapsid (27.7% versus 49.2%; P = 0.02) and anti‐spike IgG antibodies (88.2% versus 100.0%; P = 0.02) at 12 months. Lower index values of anti‐nucleocapsid IgG antibodies were also observed in transplantation patients 1 year after COVID‐19 (median, 0.49 [interquartile range, 0.15‐1.40] versus 1.36 [interquartile range, 0.53‐2.91]; P < 0.001). Vaccinated LT recipients showed higher antibody levels compared with unvaccinated patients (P < 0.001); antibody levels reached after vaccination were comparable to those observed in nontransplanted individuals (P = 0.70). In LT patients, a longer interval since transplantation (odds ratio, 1.10; 95% confidence interval, 1.01‐1.20) was independently associated with persistence of anti‐nucleocapsid IgG antibodies 1 year after infection. In conclusion, compared with nontransplanted patients, LT recipients show a lower long‐term persistence of anti–severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) antibodies. However, SARS‐CoV‐2 vaccination after COVID‐19 in LT patients achieves a significant increase in antibody levels, comparable to that of nontransplanted patients.