TNF and COVID-19: Most cytokines/chemokines are reported as upregulated in these studies (IL-2Rα, IL-4, IL-7, IL-18, IFN-γ, GM-CSF, TNF-α, CXCL10 and CXCL9) supporting the potential immunostimulatory action of this cytokine in severe COVID-19 (45).