Relevance of vitamin D(3) in COVID-19 infection

SARS-CoV-2 virus, the main culprit for COVID-19 disaster, has triggered a gust of curiosity both in the mechanism of action of this infection as well as potential risk factors for disease generation and regimentation. The prime focus of the present review, which is basically a narrative one, is in utilizing the current concepts of vitamin D(3) as an agent with myriad functions, one of them being immunocompetence and a promising weapon for both innate and adaptive immunity against COVID-19 infection. Some of the manifestations of SARS-CoV-2 virus such as Acute Respiratory Distress Syndrome (ARDS) overlap with the pathophysiological effects that are overcome due to already established role of vitamin D(3) e.g., amelioration of cytokine outburst. Additionally, the cardiovascular complications due to COVID-19 infection may also be connected to vitamin D(3) levels and the activity of its active forms. Eventually, we summarise the clinical, observational and epidemiological data of the respiratory diseases including COVID-19 disease and try to bring its association with the potential role of vitamin D(3), in particular, the activity of its active forms, circulating levels and its supplementation, against dissemination of this disease.