Predictive factors of antibody response after anti-SARS-CoV-2 vaccine in liver transplant recipients

ABSTRACT

Background: A weak immune response to 2 doses of anti SARS-CoV2 vaccine was observed in solid-organ transplant recipients. The aim of our study was to search for predictive factors of an antibody response to the vaccines and describe their efficacy and tolerance in a large population of liver transplant (LT) recipients. Methods: This is retrospective monocenter study conducted at Paul Brousse Hospital in France. All adult LT recipients followed up in our transplant center and vaccinated with at least one dose of vaccine from January 2021 to September 2021 were included. A strong immune response to vaccination was defined as the presence of antibodies titration to SARS-CoV-2 spike protein > 250 U/ml after 2nd or 3rd dose of vaccine. Results: 745 patients were included, 642 (85.5%) had 2 doses and 343 (46%) patients had three. Mean age at vaccination was 59.1(±14.5) years and mean time from LT to vaccination was 12.1 (±9.7) years. The prevalence of anti-SARS-CoV-2 antibodies was 11% (19 patients) before the first dose, 40.8% (n=53) before the second, 66.2%(n=392) before the third, and 72.5% (n=271) after the third. 190 (36.7%) patients had a strong antibody titration after 2nd injection and 139 (47.6%) after 3rd. Patients who had strong response had, in time of vaccination, lower Tacrolimus blood concentrations (p = 0.04), lower Mycophenolate (p < 0.001) and corticosteroid doses (p = 0.009) and longer time since LT (p = 0.004). In multivariate analysis, predictive factors of strong response were time since LT>9.8 years (p = 0.001), while use of corticosteroids (p < 0.001) and high mycophenolate dose (p < 0.001) were correlated with an absence of strong response. Conclusions: A strong immune response was detected to less than a half of LT recipients after 3 doses of anti-SARS-CoV-2 vaccine. These patients remain at risk for Covid-19, especially in case of high levels of immunosuppression.