CCL4 and COVID-19: Consistently, in this study we found the expression of a large number of cytokines are significantly elevated in COVID-19 patients BALF samples compared to control, including pro-inflammatory cytokines CXCL1, CXCL2, CXCL6, CXCL8, CXCL10/IP-10, CCL2/MCP-1, CCL3/MIP-1A and CCL4/MIP1B.