In adults, IFN-ɣ+ T cell frequency and activated (CD137+ CD25+) CD4+ T cells correlated after stimulation with both S-SARS-CoV-2 and N-SARS-CoV-2 at all three time points after infection (rs ranging between 0.43-0.66) and after stimulation with inactivated SARS-CoV-2 at T1 and T2 (respectively, rs=0.66 and rs=0.53) (Figure 3B). Here, CD4 is linked to infection.