What's is interesting is that Japan had, in comparison with the U.S., a low vaccination rate (though this is changing), a significantly higher population density and an almost universal conformity to mask wearing in public; far better than in the U.S. (The masks there are not all N95 by any means.) Yet Japan had, and continues to have, a significantly lower infection rate than the U.S.) I regard the lower transmission rate in Japan as due to high conformance to mask wearing. It appears that masks do, indeed, work. If they don't seem to, it is most likely due to poor conformance.