In addition, severe COVID-19 causes an increase in proinflammatory mediators, such as IL-1, IL-6, and tumor necrosis factor-alpha (TNF-α), less CD4 interferon-gamma (INF-γ) expression, and fewer CD4 and CD8 cells, which enhance susceptibility to both bacterial and fungal infections inside the body [3]. Here, CD4 is linked to COVID-19.