In this study, heVac KTRs showed overall higher spike-reactive T-cell response rates and significantly higher numbers of spike S1- and S2-reactive IFN-γ, IL-2, and bifunctional IFN-γ/IL-2- secreting cells compared to hoVac KTRs after receiving two doses of COVID-19 vaccination, which is consistent with previous reports in immunocompetent individuals (40, 41). This evidence concerns the gene IFNG and COVID-19.