SARS-CoV-2 vaccination with bnt162b2 in renal transplant patients. Risk factors for impaired response and immunological implications

Solid organ transplant patients are at higher risk for poor CoronaVirus Disease-2019 (COVID-19)-related outcomes and have been included as a priority group in the vaccination strategy worldwide. We assessed the safety and efficacy of a two-dose vaccination cycle with mRNA-based COVID-19 vaccine (BNT162b2) among 82 kidney transplant outpatients followed in our center in Rome, Italy. After a median of 43 post-vaccine days, a SARS-CoV-2 anti-Spike seroprevalence of 52.4% (n = 43/82) was observed. No impact of the vaccination on antibody-mediated rejection or graft function was observed, and no significant safety concerns were reported. Moreover, no de-novo HLA-donor-specific antibodies (DSA) were detected during the follow-up period. Only one patient with pre-vaccination HLA-DSA did not experience an increased intensity of the existing HLA-DSA. During the follow-up, only one infection (mild COVID-19) was observed in a patient after receiving the first vaccine dose. According to the multivariable logistic regression analysis, lack of seroconversion after two-dose vaccination independently associated with patient age ≥60 years (OR = 4.50; P-value = 0.02) and use of anti-metabolite as an immunosuppressant drug (OR = 5.26; P-value = 0.004). Among younger patients not taking anti-metabolites, the seroconversion rate was high (92.9%). Further larger studies are needed to assess the best COVID-19 vaccination strategy in transplanted patients.