SARS-CoV-2 infection has a strong effect on adaptive immune response, as shown by the transcriptional profile of T and B cells during the infection: the drop of circulating lymphocytes (including CD4+ and CD8+) is related to increased severity and might be due to the over-expression of genes inducing T cell apoptosis [TE83, TE89, TE110, TE111, TE112]. Here, CD4 is linked to infection.