CD4 and infection: Furthermore, although SARS-CoV-2-specific CD8+ and CD4+ T cells are elevated following infection, total T cell counts decrease during infection with SARS-CoV-2, because T cells are directly infected by SARS-CoV-2, triggering apoptosis [15,147,171,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198] (Footnotes C, D).