Transcriptome analysis of BALF samples indicated that the levels of pro-inflammatory chemokines such as CXCL1, CXCL2, CXCL6, CXCL8 (IL-8), CXCL10 (IP-10), CCL2 (MCP-1), CCL3 (MIP-1A), and CCL4 (MIP-1B) are elevated in patients with COVID-19, which correlated with disease severity. Here, CCL2 is linked to COVID-19.