Factors That Predict a Sustained Humoral Response to COVID-19 Vaccines in Kidney Transplant Recipients

Introduction Kidney transplant recipients (KTRs) produce a weak humoral response to coronavirus disease 2019 (COVID-19) vaccines. However, the factors associated with the quality of the serological response to three doses of COVID-19 vaccine have not been unambiguously identified. Methods We included KTRs followed in the Nephrology Department at Amiens University Hospital (Amiens, France) between June and December 2021 who had received three doses of a COVID-19 mRNA vaccine (or two doses plus an episode of polymerase chain reaction-confirmed COVID-19). The lack of a humoral response was defined as an antibody titer below 7.1 binding antibody units (BAU)/mL, and an optimal response was defined as an antibody titer above 264 BAU/mL. Results Of the 371 patients included, 246 (66.3%) were seropositive, and 97 (26.1%) had an optimal response. In a multivariate analysis, the only factor associated with seropositivity was a history of COVID-19 [odds ratio (OR) 87.2; 95% confidence interval (CI) (7.88–965.0); p < 0.0001], while the main factors associated with non-response were female sex [OR 0.28; 95%CI (0.15–0.51); p < 0.0001], less than 36 months between kidney transplantation and vaccination [OR 0.26; 95%CI (0.13–0.52); p < 0.0001], a higher creatinine level [OR 0.33; 95%CI (0.19–0.56); p < 0.0001], the use of tacrolimus [OR 0.23; 95%CI (0.12–0.45); p < 0.0001], the use of belatacept [OR 0.01; 95%CI (0.001–0.20); p = 0.002] and three-drug immunosuppression [OR 0.39; 95%CI (0.19–0.78); p = 0.015]. A history of COVID-19 was associated with an optimal response [OR 4.03; 95%CI (2.09–7.79); p < 0.0001], while an older age at vaccination [OR 0.97; 95%CI (0.95–0.99); p = 0.002], less than 36 months between kidney transplantation and vaccination [OR 0.35; 95%CI (0.18–0.69); p = 0.002], a higher creatinine level [OR 0.60; 95%CI (0.38–0.93); p = 0.02], three-drug immunosuppression [OR 0.45; 95%CI (0.27–0.76); p = 0.003] were associated with a poorer response. Conclusion We identified factors associated with a humoral response to a COVID-19 mRNA vaccine in KTRs. These findings might help physicians to optimize vaccination in KTRs.