CYP27B1 and COVID-19: Noticeably, vitamin D-induced mechanisms underlying the transition from proinflammatory IFN-γ+ Th1 cells to suppressive IL-10+ cells seem primed by wide-epigenetic T-cell remodeling, which promotes VDR expression and enzyme cytochrome P450 family 27 subfamily B member 1 (CYP27B1) activation by autocrine/paracrine mode, leading to Th1/Th17 program repression (via STAT3, c-JUN, and BACH2) and IL-10 enhancement (via IL-6–STAT3 signaling), as recently shown by elegant research in coronavirus disease 2019 (COVID-19) patients (130).