The COVID-19 disease course is strikingly divergent. Approximately 80-85% of patients experience mild or no symptoms, while the remainder develop severe disease.

Until treatment and vaccine for coronavirus disease-2019 (COVID-19) becomes widely available, other methods of reducing infection rates should be explored. This study used a retrospective, observational analysis of deidentified tests performed at a national clinical laboratory to determine if circulating 25-hydroxyvitamin D (25(OH)D) levels are associated with severe acute respiratory disease coronavirus 2 (SARS-CoV-2) positivity rates.

New research provides evidence of an impaired vitamin D gene signature in CD4+ T cells in patients with severe COVID-19. Mechanistically, it is shown that vitamin D alters the epigenetic landscape of CD4+ T cells, as well as inducing key transcription factors such as STAT3, BACH2 and JUN that reduce levels of IFN-γ and increase IL-10. These changes generate pro-resolving TH1 cells that may be beneficial in resolving or preventing severe COVID-19.

To investigate the association between serum 25-hydroxyvitamin D levels and its effect on adverse clinical outcomes, and parameters of immune function and mortality due to a SARS-CoV-2 infection.

The aim of the present study is to summarize existing literature on vitamin D levels in adults in different continents and different countries worldwide. The best determinant of vitamin D status is the serum concentration of 25-hydroxyvitamin D (25(OH)D).

In the preantibiotic era, TB of the skin was treated successfully with UV light. By the 1920s, pulmonary TB was being treated with regular sun exposure. During the last decade, basic laboratory research into the antimicrobial actions of vitamin D has provided new insights into these historical observations.