The characterization of the T cell subsets in a cohort of 39 COVID-19 with a median age of 64 years (range 35–94) has revealed that a decrease in both the percentage and the absolute number of naïve CD45RA+CCR7+ CD8+ T cells and in the absolute number of naïve CD45RA+CCR7+ CD4+ T cells (De Biasi et al., 2020; Belaid et al., 2021). Here, CD4 is linked to COVID-19.