IL6 and COVID-19: Severe cases of COVID-19 are associated with prolonged, heightened levels of cytokines, such as IL-6, IL-8/CXCL8, CXCL9, CXCL10, TNF-α, MCP1/CCL2, RANTES/CCL5, IL-18, and MIP-1α/CCL3, which can last for up to two months [21,32,33].