Several studies and meta-analysis suggest that vitamin D deficiency constitutes a risk factor for acute respiratory infections while supplementation may
reduce this risk. Given the current context of the COVID-19 pandemic, the role of vitamin D supplementation in the prevention and improvement of the
prognosis of affected patients has been suggested by some studies and refuted by others. Through this article, we report the mechanisms of action and
properties of vitamin D, and we discuss the different hypotheses of the involvement of vitamin D in respiratory infections, especially COVID-19 in the
light of the most recent published data.
Keywords: COVID-19, SARS-CoV-2, Vitamin D deficiency, Vitamin D supplementation, 1.25-dihydroxyvitamin D.