CXCL9 and influenza: Changes in chemokine levels in peripheral blood of COVID-19 and influenza patients have been addressed by multiple studies, in particular CXCL9, CXCL10, CXCL11, CXCL16, CCL2, and CCL5 were altered in patients as compared to controls, and levels correlated to disease severity (23, 27, 33–36).