CXCL11 and COVID-19: The most significantly elevated levels in the serum of patients with COVID-19 relative to matched healthy controls were interleukin (IL) 6; IL-6 (fold change (FC) = 7.8), C–X–C motif chemokine ligand 10; CXCL10 (FC = 8.0), CXCL11 (FC = 3.5), IFNγ (FC = 12.2), and Monocyte Chemotactic Protein-3; MCP-3 (FC = 5.1) (Fig. 1A).