Livre d'Or

Swiss cheese model: https://en.wikipedia.org/wiki/Swiss_cheese_model If none of your prophylaxes work reliably you layer them. Once you're layering them, the questions for each one are: is it safe; what does it cost; is it likely to help?

Also, RCTs are expensive and cumbersome, and inappropriate in some cases. They're especially expensive and cumbersome if you're looking for unreliable effects. You need them in medicine, because we don't understand how organisms work, but you don't need them in physics (and some of how masks are thought to work qualifies as physics).

I think masks work well enough to qualify as a layer and not well enough to rely on.

I don't see how the Cochrane authors didn't foresee that they were walking into a shitshow.