Insufficient response to mRNA SARS-CoV-2 vaccine and high incidence of severe COVID-19 in kidney transplant recipients during pandemic

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination may fail to sufficiently protect transplant recipients against coronavirus disease 2019 (COVID-19). We retrospectively evaluated COVID-19 in kidney transplant recipients (n=226) after BNT162b2mRNA vaccine administration. The control group consisted of unvaccinated patients (n=194) during the previous pandemic wave. We measured anti-spike protein immunoglobulin G (IgG) levels and cellular responses, using enzyme-linked immunosorbent spot assay, in a prospective cohort after vaccination (n=31) and recovery from COVID-19 (n=19). COVID-19 was diagnosed in 37 (16%) vaccinated and 43 (22%) unvaccinated patients. COVID-19severity was similar in both groups, with patients exhibiting a comparable need for hospitalization (41% vs. 40%, p=1.000) and mortality (14% vs. 9%, p=.726). Short posttransplant periods were associated with COVID-19 after vaccination (p<.001). Only 5 (16%) patients achieved positive SARS-CoV-2 IgG after vaccination, and 17 (89%, p<.001) recovered from COVID-19 (median IgG levels, 0.6 vs. 52.5AU/ml, p<.001). A cellular response following vaccination was present in the majority (n=22, 71%), with an increase in interleukin 2secreting T cells (p<.001). Despite detectable T cell immunity after mRNA vaccination, kidney transplant recipients remained at a high risk of severe COVID-19. Humoral responses induced by vaccination were significantly lower than that after COVID-19.