Are masks effective against coronavirus?

Unchallenged

A 2015 study in Vietnam found that those who wore cloth masks were more likely to be infected than those wearing medical masks

The study compared rates of infection—with clinical respiratory illness (CRI) and influenza-like illness (ILI)—between healthcare workers who wore disposable medical masks vs reusable cloth ones. The rates of all infection outcomes were highest among those wearing cloth masks.

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