In addition to CD38+ and CXCR3+ cells, the frequencies of CD8+ T, natural killer (NK), and B cells, and various functional populations, such as Ki-67+, TNF-α+, granzyme B+, and IFN-γ+ cells, in PBMCs and CD8+ cells did not show significant differences in old RMs after infection but showed a SARS-CoV-2-induced effect in young RMs (Fig. 6a, Supplementary Fig. 7). Here, CD38 is linked to infection.