A systematic review of the role of hypovitaminosis D in coronavirus disease-19 (COVID-19) infection and mortality: Is there a role of recommending high dose vitamin D supplementation?()

There are several studies corelating Vitamin D deficiency and risk of poorer outcomes in coronavirus disease −19 (COVID-19) patients. Our aim was to perform systematic review of the existing literature on the role of vitamin D deficiency in COVID-19 infection and mortality and whether high dose vitamin D supplementation might be helpful in reducing risk and improving outcomes. A systematic search was conducted in PubMed, EMBASE and Cochrane Library up to 5(th) June 2020. The quality of included studies was evaluated using the Downs and Black risk of bias scale. The available literature was critically appraised. 61 reports were shortlisted. After removing duplicates and reassessing eligibility, three articles were included in final review. The three included studies in this review scored from 10 to 17 (out of 31) on the risk of bias assessment tool; all of them scored low on the power criterion based on the low number of subjects included in these studies. On reporting and selection of bias, all the studies scored an average or above average. All studies failed to reach an average score on confounding. Two studies which showed positive correlation between Vitamin D levels and COVID-19 infection rates scored low on risk of bias assessment. Study showing no impact of Vitamin D scored average. There is only circumstantial evidence that links outcomes of COVID-19 and vitamin D status. Role of high dose Vitamin D against COVID-19 needs to be thoroughly evaluated in observational studies or high-quality randomized controlled studies before recommending it.