TNF and COVID-19: 1,25-dihydroxyvitamin D (1,25D), an active metabolite of vitamin D, has pleiotropic effects on immune system elements (57, 127–129) and may reduce the production of pro-inflammatory cytokines that have been implicated in the pathophysiology of COVID-19 associated ARDS (IFN-γ, TNF-α, IL-1, IL-6, IL-2, IL-12, and IL-17) (Figure 3) (130).