In SARS-CoV-2-infected adults, a transiently higher percentage of cells expressing CD38/HLA-DR was observed within the CD4+ T central memory (TCM; CD45RO+, CD27+) subset (1.1% at T1) that declined over time after infection (to 0.55% at T2, and to 0.37% at T3) and within the CD4+ terminally differentiated effector memory re‐expressing CD45RA (TEMRA; CD45RO-, CD27-, CD28-, CD57+) cell subset (0.58% at T1) that declined to 0.0% at both T2 and T3 (Supplementary Figure 2B, upper panel). Here, CD28 is linked to infection.