i assume the only true "case study" we need to look at is here in the US. look at per capita infection rates and then compare to voting records. voting records of (R) will correlate to lower mask usage. i suspect it likewise corresponds to a higher per capita infection rate.
i always look at WA state, which was ground zero (in theory) for the US-based outbreak. our numbers are quite low in comparison to many states, and that's because the bulk of the state's population is in king, snohomish, and pierce counties, in which votes heavily (D) and has good adoption of mask usage.
anecdotal, i know.
I am not a scientist, just a layman (lawyer). I'm trying to look at this myself.
To my untrained eyes, the studies supporting mask use all suffer from at least one of three flaws: (1) they looked at snapshots in time (which would be like looking at one inning of a baseball game); (2) they were anecdotal (the Missouri mask study comes to mind); or (3) they are tested in a lab, not the real world.
We live on earth and have to deal with people acting like people and behaving like people. The mask studies all talk about proper fit, proper filtration, proper material, washing masks daily, etc. It's just not what happens in the real world.
So, to your point, look at the states and see how they are doing:
Illinois has had a mask mandate since April 30. They have the most cases in the country today and the most deaths.
Wisconsin is second on the list, with a mask mandate since July 30. Second most cases.
Pennsylvania is fourth (mask mandate since July 1), Michigan is fifth (mask mandate since May 15).
Sandwiched in between all of these is Florida, which has not had a mask mandate since September. As noted previously, the Dakotas are also experiencing high per capita case counts/hospitalizations.
Now, maybe it's the red areas. But just for example, I look at the Michigan county-by-county map, and the Democratic areas have the most cases. Now, that map is a little difficult, because you'd like to see per capita, but it is what it is.
https://www.michigan.gov/coronavirus/0,9753,7-406-98163_98173---,00.htmlFrom my completely anecdotal experience, people bitch about masks but wear them (including me). I always wear one at work, at the grocery store, etc. I'd estimate Ohio's compliance at 90%. We are hitting our surge, hard, now.
In any event, I would love a fifty state survey of all these policies. But just looking at things, I just do not see statistically significant correlations between NPIs and outcomes.
And that is probably my biggest frustration. COVID might be the ultimate Rorschach test -- you see what you want to see. The only reason I return to this thread is to be reminded of my biases. I try to confront them, the discussion here being one of the useful tools.
But again, I'm just looking at the data, and I don't see much of a correlation with NPI's and outcomes. The NPI's are all theoretical and have never been tried on this widespread of a basis.
And that's probably my ultimate point -- I have no doubt that these policies all theoretically make sense (including masks) in a lab or in some sort of computer simulation -- but we live on earth, and that's not how things work.