Mask compliance does not reduce covid-19 transmission. Did we know it from the start?

Data from Europe:
www.ncbi.nlm.nih.gov/pmc/articles/PMC9123350

Abstract: "... These findings indicate that countries with high levels of mask compliance did not perform better than those with low mask usage."




And CDC study shows that mask usage doesn't help elementary schools:
www.cdc.gov/mmwr/volumes/70/wr/mm7021e1.htm

"... The 21% lower incidence in schools that required mask use among students was not statistically significant compared with schools where mask use was optional."
Mask compliance does not reduce covid-19 transmission. Did we know it from the start?
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