[User23]

RCTs show surgical and cloth masks to be ineffective or nearly so for reducing the spread of respiratory viruses. Obviously the kinds of masks used in BSL labs do work to prevent spread.

However there are statistics that areas with more masking had less severe illness. However that’s uncontrolled and some other factors or factors might account for both increased masking and reduced spread. That’s probably the case otherwise the RCTs would show efficacy.

All of the subsequent work is just computer models and doesn’t actually tell us anything empirical. Obviously it’s easier to create a model that produces the desired result than it is an RCT.