Here’s what we know: It takes a lot to get people to wear masks. Information campaigns have a fairly limited effect. Mandates have a much larger one. “A general stylized fact in behavioral economics,” Abaluck told me, is that “it is very hard to get people to do anything differently than they were doing beforehand.”

Increases in mask-wearing do appear to reduce disease transmission during a pandemic, though it’s hard to extrapolate how large that increase would be if everyone wore masks.

Source: The controversy over the Cochrane review on Covid masks, explained – Vox