A room full of flu patients and no one got sick

In a striking real-world experiment, flu patients spent days indoors with healthy volunteers, but the virus never spread. Researchers found that limited coughing and well-mixed indoor air kept virus levels low, even with close contact. Age may have helped too, since middle-aged adults are less likely to catch the flu than younger people. The results highlight ventilation, air movement, and masks as key defenses against infection.

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