[James_Henry]

>This is of course only meaningful if almost everyone wears something. This is true at the moment.

It's not true that you need almost everyone wearing something. Jeremy Howard wrote

>Studies have documented definitively that in controlled environments like airplanes, people with masks rarely infect others and rarely become infected themselves, while those without masks more easily infect others or become infected themselves.

>Masks don’t have to be complex to be effective. A 2013 paper tested a variety of household materials and found that something as simple as two layers of a cotton T-shirt is highly effective at blocking virus particles of a wide range of sizes. Oxford University found evidence this month for the effectiveness of simple fabric mouth and nose covers to be so compelling they now are officially acceptable for use in a hospital in many situations.

http://archive.vn/Dlabz#selection-1639.0-1653.170

[megous]

Does that assume that infected people know who they are?

[James_Henry]

Sorry, I think I was confused by the "This" in your sentence that I quoted. I meant to point out that a mask protects you directly (if you are not sick) and not just by lowering the spread of the disease throughout the population. It seems that you actually agree and I misunderstood.