A University of Louisville study released in May 2022 found that mask mandates and greater compliance resulting from them "did not predict lower growth rates when community spread was low (minima) or high (maxima)." The study, which used CDC data across several seasons, found that mask usage and mandates "are not associated with lower SARS-CoV-2 spread among US states."
Remember that CDC study purporting to show that school masking was effective? Did you wonder what the results would have been if someone had conducted a higher quality study over a greater sample size and period of time? Ambarish Chandra of University of Toronto and Dr. Tracy Hoeg of University of California, Davis did exactly that with this Lancet study titled, "Revisiting Pediatric COVID-19 Cases in Counties With and Without School Mask Requirements—United States, July 1—October 20 2021." Their results: "... no significant relationship between mask mandates and case rates." Color me shocked.