Narrative Review of Systematic Reviews on the Roles of Vitamin D in the Era of COVID-19 Pandemic

ABSTRACT

@#The severe acute respiratory syndrome coronavirus-2 (SARS-CoV2) virus has caused a worldwide COVID-19 pandemic. Vitamin D deficiency and insufficiency may have a significant impact on respiratory viral infections. This narrative review of systematic reviews describes the roles of vitamin D on COVID- 19 infection prognosis and whether vitamin D supplementation has any role in improving clinical outcomes of COVID-19 patients. A literature search of PubMed and Google Scholar was conducted in October 2021. Only systematic reviews published in the English language from January 2020 through October 2021 were included. Seven systematic reviews were identified. Five showed that low vitamin D levels increased the likelihood of contracting COVID-19 infections, admission into intensive care and increased mortality for severe vitamin D deficient individuals. Two reviewed the benefits of vitamin D supplementation and found an association between supplementation and a reduction in ICU admissions and mortality from COVID-19 infections. All of the systematic reviews identified a high prevalence of vitamin D deficiency in COVID-19 individuals, with a positive correlation between vitamin D deficiency and disease severity. Maintaining appropriate levels of vitamin D through oral supplementation or sunlight exposure may be beneficial to improve public resilience during this pandemic.