[iNane9000]

Only properly fitted n95 masks, which require professional training to use properly.

[m4rtink]

Also, all involved in close contact need a mask, as infected people with a mask are much less likely to infect others.

[deregulateMed]

I don't disagree. If we spent 4 trillion dollars on n95 masks and training, we'd have 1% more people alive and saved money.