TNF and COVID-19: It has been reported that patients with COVID-19 reduce plasma cells, pro-inflammatory cytokines [including IL-6, IL-10, granulocyte-colony stimulating factor, macrophage inflammatory protein, tumor necrosis factor-α (TNF-α)] (32), and vitamin D has been shown to increase macrophages' response, anti-inflammatory cytokine production, and activating Toll-like receptors and thus suppress the cytokine storm and pathogenic inflammation during COVID-19 infection (33, 34) (Figure 11).