CD4 and COVID-19: These data may confirm our findings showing a positive correlation between serum IgG levels for CMV and the proportion of senescent T cells, defined as CD28−CD57+ (for both CD4+ and CD8+ T cells), in the Allele-1 group following vaccination, and also allow us to speculate that these associations may influence and lead to an altered COVID-19 immune response encompassing both SARS-CoV-2 infection and vaccination.