Petrelli et al., The Journal of Steroid Biochemistry and Molecular Biology,
doi:10.1016/j.jsbmb.2021.105883 (Peer Reviewed) (meta analysis)
Therapeutic and prognostic role of vitamin D for COVID-19 infection: A systematic review and meta-analysis of 43 observational studies
Meta analysis showing vitamin D deficiency associated with higher risk of COVID-19, worse severity, and higher mortality.
Supplementation with vitamin D reduced the risk of severe cases and mortality.
Petrelli et al., 3/26/2021, peer-reviewed, 6 authors.