CD8A and COVID-19: There was a significant correlation between worst COVID-19 outcome on the 8-point scale and activated cTfh cells (P = 0.005) and between worst COVID-19 outcome on the 8-point scale and both CD38 and HLA-DR upregulation on CD4+ T cells (P = 0.008) and CD8+ T cells (P = 0.002) (Figure 7).