Could a vitamin d boost make flu shots work better for seniors?
NCT ID NCT01893385
First seen Aug 06, 2026 · Last updated Aug 07, 2026 · Updated 1 time
Summary
This trial tests whether giving older adults a high dose of vitamin D before their flu shot can strengthen their immune response. Participants are 65 or older with low vitamin D levels. The study measures changes in infection-fighting proteins and antibody levels after vaccination, to see if correcting vitamin D deficiency helps the body respond better to the flu vaccine.
What this could mean
Our plain-language read of the trial. This is informational only — not medical advice or a prediction.
- Active substance
- Vitamin D (as a single high-dose supplement, 100,000 IU) given alongside the seasonal influenza vaccine
- What this could lead to
- If vitamin D boosts the immune response to flu vaccination in older adults, it could point toward a simple, low-cost way to strengthen protection against flu and other infections in aging populations.
- What could go wrong
- This is a small, early-stage trial, so results may not apply broadly. Vitamin D may not meaningfully change immune response, and high-dose supplements carry a small risk of side effects like elevated calcium levels.
This is an AI summary of the original study and may miss details. Read our disclaimer.
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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
Locations
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CHU Clermont-Ferrand
Clermont-Ferrand, 63003, France