Can vitamin d stop COVID-19? large trial tests high doses
NCT ID NCT04536298
First seen Jun 26, 2026 · Last updated Jun 26, 2026
Summary
This large study tested whether high-dose vitamin D3 supplements could help people recently diagnosed with COVID-19 avoid severe illness and also prevent the virus from spreading to their household members. Over 2,000 participants across the U.S. and Mongolia took either vitamin D or a placebo for 4 weeks. The goal was to see if vitamin D reduces healthcare visits and infections in close contacts.
What this could mean
Our plain-language read of the trial. This is informational only — not medical advice or a prediction.
Active substance
vitamin D3 (cholecalciferol) dietary supplement
What this could lead to
If it works, this could point toward a simple, low-cost way to reduce COVID-19 severity and prevent household spread.
What could go wrong
This is a completed Phase 3 trial, but vitamin D's effect on COVID-19 has been mixed in other studies. High doses may cause side effects like kidney stones.
Disclaimer
Read more
Show less
This is a summary of
the original study
.
Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.
This is a summary of the original study . Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.
Get updates
Get notified about this study
Sign up to get updates when this study changes or when new studies for COVID-19 are added.
By submitting, you agree to our Terms of use
Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Show contact details
Enter your email to view the contact information for this study.
By submitting, you agree to our Terms of use
Locations
-
Brigham and Women's Hospital
Boston, Massachusetts, 02215, United States