Severe COVID-19 is characterized by high levels of inflammatory mediators; including interleukins IL-2, IL-6, IL-7, IL-10, TNF-α (tumor necrosis factor alpha), and chemokines such as IP-10 (interferon γ-induced protein 10kDa) and MCP-1 (monocyte chemoattractant protein 1), together with profound lymphopenia​. This evidence concerns the gene CCL2 and lymphopenia.