A study in a French nursing home found an 89% decrease in mortality in residents who had received high-dose vitamin D either shortly before or during covid-19 disease.

(vitamin D) Annweiler, C., Hannotte, B., Grandin de l’Eprevier, C. et al. Vitamin D and survival in COVID-19 patients: A quasi-experimental study. The Journal of Steroid Biochemistry and Molecular Biology. November 2020. https://doi.org/10.1016/j.jsbmb.2020.105771.