CCL2 and acute respiratory distress syndrome: This is because the influx of those pro-inflammatory cytokines such as TNF-α, interleukin (IL)-2, IL-7, IL-10, macrophage inflammatory protein-1A (MIP-1A), and monocyte chemoattractant protein-1 (MCP-1) found in critically ill COVID–19 patients may cause acute respiratory distress syndrome (ARDS), which is the main cause of their death [25–27].