This is from a small (50 subjects) but seemingly rigorous study on the mitigating effect of high doses of Vitamin D on Covid-19.
Of course, studies like this one are coming out fast and furious so take this with a grain of salt, but I’m interested in seeing corroboration of this result because it could be a freely available and inexpensive way for everyone to reduce their risk of developing serious complications.
Our pilot study demonstrated that administration of a high dose of Calcifediol or 25-hydroxyvitamin D, a main metabolite of vitamin D endocrine system, significantly reduced the need for ICU treatment of patients requiring hospitalization due to proven COVID-19. Calcifediol seems to be able to reduce severity of the disease, but larger trials with groups properly matched will be required to show a definitive answer.