Additional studies have also revealed that patients with severe COVID-19 have a significantly elevated cytokine profile of IL-2, IL-6, IL-7, IL-10, IP-10, MCP-1, TNF-α, macrophage inflammatory protein 1 alpha, and granulocyte-CSF compared to patients with mild to moderate COVID-19 (Hu et al., 2021). Here, IL7 is linked to COVID-19.