Serum of COVID-19 patients is characterized by increased levels of the following: IL-2, IL-7, IL-10, TNF-α, protein monocyte chemoattractant-1 (MCP1; also known as C-C motif chemokine ligand 2 CCL2), granulocyte colony-stimulating factor (G-CSF), macrophage inflammatory protein 1 alpha (MIP1α; also known as CCL3), C-X-C motif chemokine ligand 10 (CXCL10), C-reactive protein (CRP), D-dimers and ferritin (19, 38–40). Here, CCL2 is linked to COVID-19.