I've reread the relevant CDC and Vox recommendations on masks. They both need to updated, to remove ambiguity, to be more strenuous.

Because worksmithing is hard, here's what I proposed to Vox's German Lopez:

"Wide spread mask usage greatly slows the spread of coronavirus.

The combination of masks, social distancing, wide spread testing, temperature screening, contact tracing, and quarantines works.

Everyone should wear masks to protect other people. If you are high risk, wear a N95 respirator to protect yourself. Because healthcare and first responders need more protection than you, please don’t use an N95 until we have a supply surplus.

To clarify the effective difference between respirators and masks: N95 rated respirators are form fitting with better filters, so all air goes thru the filter; while surgical and cloth masks still allow some unfiltered air, they do catch most exhaled airborne water droplets (moisture), effectively slowing the spread."

Thank you again for sharing your find.

I think it depends on perspective. There is not evidence that surgical masks useful in preventing someone from contracting covid [0]. Which makes sense because droplets can still be inhaled because air flows around the mask (unlike n95 respirators).

Masks are very useful in preventing spread, thus useful for overall slowing the spread of the disease.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118603/

Great find, thanks.

That review of the paper makes the distinction between protection and transmission. I admit I was only thinking about protection.

Since I'm immunocompromised, I will continue to wear N95 respirators whenever I'm around other people.

But per this paper, surgical masks are useful for "source control", at least partially thwarting infected people from spreading the virus. I'm super skeptical, because of old habits, but science is science.

So the rest of you should start wearing surgical (or cloth) masks. Thanks.