IL6 and COVID-19: Halim et al. studied the association between TNF-α, IL-6, vitamin D levels, and COVID-19 severity and mortality, and found: (1) insignificant differences in mean vitamin D levels between patients with severe COVID-19 and non-severe COVID-19, (2) insignificant increased risk of COVID-19 severity associated with TNF-α, (3) significant increased risk of COVID-19 mortality associated with TNF- α, and (4) IL-6 as an independent prognostic factor for COVID-19 severity and mortality [58].