These cells release proinflammatory factors represented by granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-6, which recruit more inflammatory cells into the lungs and other organs to form a “cytokine release syndrome”, and the further aggravated inflammatory storm will eventually lead to multiorgan failure and death in patients with severe COVID-19 (22–24). Here, CSF2 is linked to COVID-19.