CXCL17 and COVID-19: Conversely, discrepancies in the immune signature of these infections include higher levels of Th1 cytokines along with IL-2, APRIL, sTNF-R1, sTNF-R2, SP-D, and CXCL17 in severe influenza patients, with COVID-19 displaying a polyfunctional Th1/Th2/Th17 immune activation profile in some patients with severe manifestations.