CD8A and COVID-19: As shown in Figure 5E, we segregated patients into 2 groups — those who recovered and those who died from COVID-19 — and compared their relative risk using a Cox proportional hazard model with other confounding factors, including age, gender, hypertension (HT), and obesity and the 2 main features of adaptive T cell immune responses to the virus, i.e., the proportion of NC cytokine-secreting CD8+ T cells and Teff CXCR3+PD-L1+CD8+ T cells.