The Effect Vitamin D Supplementation on Severity and Mortality Risk of COVID-19: A Systematic Review

Vitamin D levels are associated with improved immunity dysregulation to prevent worsening of COVID-19 patients. However, studies regarding the effects of vitamin D on COVID-19 patients are still inconsistent. This study aimed to analyze vitamin D supplementation's effect on the severity and mortality risk of COVID-19 patients. Search was conducted in seven databases on September 2020. Studies assessing the topic were included without study design restrictions. Four studies were included in this study. All reported risk of mortality, and three reported of severity degree. Two of the three found patients with vitamin D supplementation had a significantly lower risk of disease. One other found no significant difference, although a higher proportion of severe COVID-19 was recorded in the group without supplementation. Three of the four reported supplementation as a protective factor against mortality in COVID-19 patients. One study reported that vitamin D supplementation group had a higher mortality than the group without, although it has low validity and high risk of bias. In conclusion, there were differences in the severity and mortality risk between COVID-19 patients given vitamin D supplementation and control patients. Vitamin D supplementation is a protective factor in the severity and mortality risk of COVID-19 patients.