Face masks help prevent people from getting the flu. But how much protection do they provide?
You might think the answer to this question would be well established. It’s not.
In fact, there is considerable uncertainty over how well face masks guard against influenza when people use them outside of hospitals and other health care settings. This has been a topic of discussion and debate in infectious disease circles since the 2009 H1N1 flu pandemic, also known as swine flu.