IL4 and COVID-19: The cytokine storm has already been attenuated following recovery from COVID-19, as levels of TNF-α, free active TGF-β, IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17 and MCP-1/CCL2 during convalescence were not higher compared to healthy volunteers.