ABSTRACT
Background: There is limited data on the safety and efficacy of SARS-CoV-2 mRNA vaccines in kidney transplant recipients (KTRs). Methods: We conducted a prospective, multi-center study of 58 adult KTRs receiving mRNA-BNT162b2 or mRNA-1273 vaccines to assess vaccine safety and efficacy. Primary outcome was biopsy-proven rejection within 3 months of vaccination. Secondary outcomes included adverse events, serum creatinine, proteinuria, donor-derived cell-free DNA (ddcfDNA) levels, and antibody and cellular immunity generation against SARSCoV-2. Results: Median age was 62 with 41% females. Median time post-transplantation was 48 months. Only one patient (2%) developed acute cellular rejection though patient had been recently converted to belatacept. There were no severe adverse events or deaths during follow-up. Two patients (3%) developed SARS-CoV-2 infection, one of whom required hospitalization. There was no significant change in serum creatinine, proteinuria or ddcfDNA during the study. Following vaccination, 36%, 25% and 20% of KTRs developed anti-spike, anti-S1 and anti-RBD antibodies. KTRs on mycophenolate-based and steroid-maintenance regimens were less likely to develop an anti-spike antibody response. 100% of KTRs with anti-spike and anti-RBD antibodies had a neutralizing response, compared to 44% in KTRs with anti-spike but without anti-RBD antibodies (RR 2.25, 95% CI 1.08-4.67). There was a significant increase in IFN-gamma spots per 106 PBMCs incubated with S1 peptides following vaccination (p=0.0143). Conclusions: SARS-CoV-2 vaccination in KTRs was safe and associated with the generation of cellular immune response and in a third of patients with anti-spike antibody response. The degree of protection gained by these responses needs to be evaluated in future studies.