CCL3 and COVID-19: This included higher concentrations of multiple mediators closely associated with severe COVID-19 and reflective of pro-inflammatory myeloid and NK cell differentiation, activation, and chemotaxis (IL-6, IL-8, IL-15, MCP-3, G-CSF, M-CSF, CXCL9, CCL3, CCL4, lymphotoxin-α, TNF) (Fig. 4a, Supplementary Table 7).