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 antibody- positive 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 administered CD20 antibody (rituximab) before and/or after transplant showed a lower production of antibodies, which was supported by a smaller number of CD19- and CD20-positive cells in the peripheral blood as well as a shorter period between rituximab administration and vaccination. The percentage of responding viral fragments varied greatly among individual patients and showed no uniformity in the kidney transplant group, whereas the mean fluorescence intensity of individual fragments showed a certain tendency in the control group.

CONCLUSIONS

The appropriate timing of vaccination should be considered in transplant recipients who use tacrolimus-mycophenolate mofetil combination and rituximab as these drugs are deeply related to a lower antibody response to SARS-CoV-2 BNT162b2 vaccination.