CD38 and COVID-19: Similar dynamics occurred for CD38+HLA-DR− and CD38−HLA-DR− CD4 naïve T cells which showed an increase and decrease, respectively, over time in the severe COVID-19 group (Spearman’s rank correlation; CD38+HLA-DR− CD4 naive: R2 = 0.42, P = 5.8 × 10−4; CD38−HLA-DR− CD4 naive: R2 = 0.42, P < 6.5 × 10−4) with later timepoints reaching levels observed in unexposed healthy individuals (Fig. 2c).