According to the collected data, both percentages (Table 4) and absolute counts (Figure 2) of different studied T cell subtypes including CD3+ cells, CD4+ cells, CD8+ cells, CD4+CD25+ cells, CD38+ cells, CD4+CD38+ cells, and CD8+CD38+ cells in different patient groups showed a significant decrease between healthy control and COVID-19 patient groups. Here, CD4 is linked to COVID-19.