by exhaling water vapor that has the virus attached to it, and that floating around in the air until it's inhaled by someone else. The old thinking is it was transmitted much like the cold/flu, meaning by coughing/sneezing or by rubbing your eye/nose/mouth then touching something that someone else can touch after you.

Which is all well and good, and helpful to know. The issue from a policy perspective is some need security theater of a visible marker that a person is being careful. To date, that has been wearing a mask since displaying a vax card has its own issues. If this were spread by coughing/sneezing or by touching your face, then a mask is actually a pretty good preventive measure. But if it's spread more by exhaling than by coughing/sneezing, anything short of an N95 or full-on respirator is darned near useless.

If you genuinely want to know what is effective at protecting yourself and others without all the noise of security theater or partisan politics, good luck figuring it out.