CD4 and infection: Previous studies have reported differences in the expression of activation markers on SARS-CoV-2 specific memory CD4+ T-cells between exposed but SARS-CoV-2 seronegative individuals, compared to those who had either mild or severe infections [11]; however, to our knowledge, this is the first report of elevated activation of T-cells by MHC/TCR crosslinking (i.e., Cytostim) in convalescent COVID-19 patients.