Can a simple mask stop the flu? 2,000 volunteers put it to the test

NCT ID NCT07739446

First seen Jul 31, 2026 · Last updated Aug 04, 2026 · Updated 2 times

Summary

This trial asks whether wearing a surgical mask every day can prevent acute respiratory infections like influenza and COVID-19. About 2,000 adults who normally don't wear masks will be randomly assigned to either wear a mask when outdoors or continue without one for 3–4 months during flu season. Participants will report symptoms and testing results every two weeks. The study focuses on whether masks protect the wearer, not on preventing transmission from sick individuals or the effects of universal masking.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance
Surgical masks worn daily
What this could lead to
If wearing a mask every day proves effective, it could support simple, low-cost guidance for reducing flu and COVID-19 infections during respiratory season.
What could go wrong
This trial only tests personal protection, not preventing spread from sick people or universal masking. Results may vary by adherence and virus activity, and the study is not designed to prove masks work in all settings.

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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

  • Chiba University/National Institute of Infectious Diseases, Japan Institute for Health Security

    Chiba, Japan

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