Those CD8+ T-cells that were present were found to be highly activated in a subset of COVID-19 patients as measured by KI67 and HLA-DR+CD38 expression (161) and appear to retain their cytotoxic capacity as measured by IFNγ, granzyme B, perforin, and CD107a production or expression (137) (Figure 2C). This evidence concerns the gene CD8A and COVID-19.