Biggest mask study so far: https://med.stanford.edu/news/all-news/2021/09/surgical-masks-covid-19.html https://med.stanford.edu/news/all-news/2021/09/surgical-

Biggest mask study so far: https://med.stanford.edu/news/all-news/2021/09/surgical-masks-covid-19.html https://med.stanford.edu/news/all-news/2021/09/surgical-mask... Cloth masks don't work at all, and surgical masks only reduce infections by 11%. N95s are probably a lot more effective but this study didn't measure those.