Below are resources providing information about what we know about Vitamin D and Covid-19:
Lanham-New S, Webb AR, Cashman KD, Buttriss JL, Fallowfield JL, Masud T, et al. Vitamin D and SARS-CoV-2 virus/COVID-19 disease. BMJ Nutrition, Prevention & Health. 2020;0. doi:10.1136/ bmjnph-2020-000089. Article available from: https://nutrition.bmj.com/content/early/2020/05/15/bmjnph-2020-000089
Covid-19 ClinicalTrials.gov site from the U.S. National Library of Medicine list studies examining questions about vitamin D
The Bottom Line:
PEN continues to endorse the international recommended intakes for Vitamin D and recognize that it is possible that those who are Vitamin D deficient could be at increased risk of contracting COVID-19 or for having a more severe disease course. However, at this point in time these ideas are based on speculation and indirect evidence.
There is no harm from promoting the international recommended intakes for Vitamin D but higher doses, such as those greater than the tolerable upper limit, are not justified.
For additional information see International Reference Values Collection