Still, masks do appear to help. It’s straightforward: Coronavirus appears to mostly spread when germ-containing droplets make it into a person’s mouth, nose, or eyes. If you have a physical barrier in front of your mouth and nose, that’s simply less likely to happen.
But the best protection masks offer may be protection from the wearer. While the evidence is thin on how much masks protect the wearer from coronavirus — since it’s unclear if the virus spreads much through airborne droplets — it’s true that the masks stop people from spreading their own droplets: When you breathe, talk, laugh, sigh, yawn, sneeze, or cough in public, you’re less likely to get droplets on a checkout machine, dining table, or anywhere else if you have a mask on. That could stop people, even those who are asymptomatic, from spreading infection.