TNF and COVID-19: Further IFN-γ activation by these cells leads to additional cytokine and chemokine signals [IFN-γ, TNF-α, C-C motif chemokine ligand (CCL)2, CCL7, and CCL12] that enhance infiltration and activation of monocytes and neutrophils, further exacerbating the inflammatory response and inducing high cytokine levels, a phenomenon referred to as cytokine storm, which has been linked to more severe manifestations of COVID-19 (60).