Vitamin D insufficiency as a potential culprit in critical COVID-19 patients.

<h4>Background</h4>As an immune modulator, vitamin D has been implicated in the coronavirus disease-2019 (COVID-19) outcome. We aim to systematically explore the association of vitamin D serum levels with COVID-19 severity and prognosis.<h4>Methods</h4>The standardized mean difference (SMD) or odds ... View More