If it’s not true that you can infect other people if you have covid but are not showing symptoms, then there’s no reason at all to wear masks, even if masks worked.

Because if you could only infect people when you show symptoms — well, if you show symptoms, you stay home and self-isolate. You don’t need to wear a mask in public because you’re already not in public.

A new study shows that people who are presymptomatic cannot, in fact, spread covid. Or at least, they can’t spread it except in “rare” cases.

[Ace also mentions the Cochrane metastudy that concluded there was no evidence that masking stopped transmission in any meaningful manner, not even with N-95 masks. — Ed]