CD4 and COVID-19: A third study suggests increased proportions of SARS-CoV-2 reactive cytotoxic TFH cells with dysfunctional/exhausted gene signatures and of clonally expanded cytotoxic CD4 TH cells producing myeloid cell attracting chemokines; but under-represented SARS-CoV-2 reactive suppressive Treg cells and polyfunctional TH1 and TH17 cells in severe vs. mild COVID-19 (44).