
CDC reports masks prevented Covid spread at a hair salon - mleonhard
https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e2.htm
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rossdavidh
Maybe I'm missing it, but it doesn't seem to show anything that says that it
was masks that prevented Covid spread? There wasn't a non-mask control
(unsurprisingly, in an unplanned experiment), and we don't have a good
comparison for how high the rate of transmission is expected to be in similar
conditions without masks.

None of which means masks _didn't_ help, but I don't see anything in here that
shows evidence that masks _did_ help. Unless there's a comparison here that
I'm missing?

