CXCL9 and COVID-19: The following chemokines play the most important role in COVID-19 progression: monocyte chemoattractant protein-1 (MCP-1/CCL2), macrophage inflammatory protein-1 alpha (MIP-1 α/CCL3), macrophage inflammatory protein 1-beta (MIP-1 β/CCL4), regulated upon activation, normal T-cell expressed and secreted (RANTES/CCL5), monokine induced by γ-interferon (MIG/CXCL9), and interferon-inducible protein (IP-10/CXCL10) (6–8).