Mason  🏃‍♂️ ✂️

I think "30% hurts" is *really* high. No study is perfect, but the one everyone is passing around does not, in any meaningful sense, have a control group. Second, looking at health workers who'd be at high risk even in full PPE w/ decontamination protocols doesn't tell us much.

yeah, that's fair. Divia's point (that having a reservoir close to your face potentially matters a lot for bacteria, and can't for viruses) made me update a little; I'd probably put it lower now

I'm curious where that 30% is coming from. is it a specific model of how harm could happen? or just a general "medicine is messy we should be less confident" thing?

impression that medical studies that are counterintuitive and not extremely methodologically strong replicate like 30% of the time

I mean, here's how I'm reading this study: 1) throw out the control group; it's genuinely worse than useless as described — for all we know, they always wore a medical mask in close contact with the sick 2) conclude that medical masks work better than cloth masks — makes sense!

Hmmm, I think you can do better than my 30% heuristic here but throwing out the control group, the study still finds that the difference between surgical and cloth is too large to be consistent with cloth being net-positive unless surgical is much much better than anyone thought

Well, my follow-up assumption is that neither medical masks nor cloth masks work well if your full-time job is with infectious patients; the point at which you reach "zero difference" depends on how long you run the study, how infectious the patient pop is, etc.

This is the reason it was a big no-no to pull in the "medical masks don't work" assumption from other studies, where those factors were almost certainly different