CD38 and lymphopenia: Given the condition of lymphopenia, which also affects circulating γδ T lymphocytes in these patients, it has been hypothesized that SARS-CoV-2 infection may induce a switch to a depleted phenotype or a condition of hyperactivation; this is supported by results that report overexpression of activation markers (CD38, HLA-DR, CD25) and genes encoding pro-apoptotic molecules (NFRSF10B/TRAIL-R and CASP3/Caspase 3) [45,53].