Vitamin D and SARS-CoV-2.

The single-stranded RNA virus, SARS-CoV-2, causing the COVID-19 pandemic, has severely impacted daily life globally. It has been suggested to supplement the general population with vitamin D to reduce the impact of COVID-19. Nevertheless, no clear consensus can be found as to whether vitamin D affects COVID-19 disease burden. Some studies found that vitamin D levels and/or vitamin D supplementation alleviated COVID-19 disease severity and mortality. Contrarily, other studies found no such effects of vitamin D. To understand this lack of consensus, it is relevant to investigate molecular studies of the vitamin D receptor (VDR), as such studies might explain apparent controversies. We have investigated recent studies of how transcriptional regulation by the VDR affects the immune response against SARS-CoV-2. One study found that cells from severe COVID-19 patients displayed a dysregulated vitamin D response. Contrarily, another study observed a normal immune response towards SARS-CoV-2 in a patient with a non-functional VDR. These observations indicate that hypovitaminosis D is not a prerequisite for an efficient immune response against SARS-CoV-2 and therefore not a driving factor for developing severe COVID-19. However, should a patient develop severe COVID-19, vitamin D seems to be beneficial potentially by dampening the cytokine storm.