Antibody Response to SARS-CoV-2 mRNA Vaccine Among Kidney Transplant Recipients: A Retrospective Cohort Study at a Single Transplant Institute in Japan

Objectives: Although the effectiveness of vaccines in protecting the host from infection has been proven, few surveys have been conducted on changes in antibody levels after vaccination of kidney transplant recipients in Japan. Materials and Methods: We analyzed serological responses in kidney transplant recipients after BNT162B2 COVID-19 mRNA vaccine with the use of a reagent capable of simultaneously specifying the antibody response to 5 proteins: a full-spike protein (extracellular domain), 3 individual domains of the spike protein (S1, S2, and receptor-binding domain), and nucleocapsid. The analysis involved 111 patients who had follow-up over 1 month after having received the second of 2 coronavirus vaccines after kidney transplant. Results: Antibodies were detected in 46 of 111 patients (41%). The antibody-positive rate in the kidney transplant group tended to be lower than that in the healthy control group, which showed an antibodypositive rate of 100%. When the antibody-positive rate was analyzed by the type of immunosuppressor used, the rate was 36% (37/100) for patients who used tacrolimus at the time of vaccination and 90% (9/10) for patients who used cyclosporine. Patients