In summary, our data indicated that a homologous mRNA COVID-19 vaccine 3D exerts a booster effect on anti-RBD antibodies, NtAb binding to SARS-CoV-2 ancestral and variants of concern (Delta and Omicron), and SARS-CoV-2-S- IFN-γ-producing T cells in HD patients, although this effect appeared to be of a lower magnitude in KTR patients. The gene discussed is IFNG; the disease is COVID-19.