CCL2 and COVID-19: Many studies [7, 46, 51, 56–62] of CS confirmed that levels of IL-2, IL-7, IL-10, TNF-α, granulocyte colony-stimulating factor (G-CSF), IP-10, MCP-1, and macrophage inflammatory protein 1-alpha (MIP-1α) were significantly higher in patients admitted to the ICU for COVID-19, although other studies [7] demonstrated little difference between IL-4, IL-17, and TNF and significant differences in IL-6 and IL-10 levels, suggesting a systemic inflammatory process in critically ill patients.