> There is no control group There's no ethical way to do a control in a study of infectious diseases. You'd have to mandate that some study participants not w

> There is no control group There's no ethical way to do a control in a study of infectious diseases. You'd have to mandate that some study participants not wear masks, when your hypothesis is clearly they the masks will keep some of them from getting sick or dying. You're asking for far too much here. Masks are known to stop disease spread from (literally) centuries of use. We don't have to throw all that intuition out with covid, even though the numbers may change. And again: why should we have to prove this technique via completely impractical research constraints when it is very likely that it helps, in a situation of dire urgency.