They did. Also, mandates and lockdowns are only as good as the people who comply.
Researchers said results highlight the need to continue with face coverings, social distancing and handwashing alongside vaccine programmes
www.theguardian.com
Researchers found that surgical masks impede the spread of COVID-19 and that just a few, low-cost interventions increase mask-wearing compliance.
med.stanford.edu
This report describes Arizona school associated COVID-19 outbreaks higher in schools without mask requirements than in schools with mask requirements.
www.cdc.gov
This report describes pediatric COVID-19 cases in counties with and without school mask requirements.
www.cdc.gov
This report describes changes in COVID-19 case and death growth ...
www.cdc.gov
This report describes COVID-19 incidence in Kansas counties with and without mask mandates.
www.cdc.gov
www.vumc.org
Several of these studies have been either completely debunked, admitted extreme bias, or are observational versus running actual trials,with a control group. Observational studies that look for correlations are cute, but they aren't as good as cluster randomized control trials that actually control and test the variable in question. You have to have an equal baseline between two groups to see if the variable in question actually has an impact (in this case masks).
The Arizona study, which is what the cdc has relied on for their mask guidance, has been completely debunked. The study did not account for vaccination rates, community transmission at the time the study started and used different periods of time that schools were open. Some were open six weeks and some were open 3 weeks or less and pointed to as proof mask mandates work. It also included virtual schools in their population. It's a crap study and anyone who understands data should know that at this point. The fact that study is the basis for masking kids in schools is a joke.
The one referenced in the guardian, the authors admitted it was biased.
Those others I admittedly haven't read but appear to be observational studies. Which are not in the same league as cluster randomized control trials. The best CRT on masks and covid was out of Bangledesh and done prior to even delta. That study concluded cloth masks had a 2% reduction in Covid....but that wasn't statistically significant so your best case scenario (based on the actual science) is pre-delta cloth masks reduce less than 2%. The study itself states that reductions in covid due to cloth masks were statistically insignificant which means any reduction is just as likely to have occurred due to random factors as it was masks. With delta and omicron any benefit is likely gone.
Surgical masks were better- 11% reduction, but that number is likely reduced because of the transmissability of delta and omicron. And at this point do we think, as a society, it is worth masking entire populations, and kids for less than 11% reduction in spread, especially with vaccines available? Any sane person would say no.
Then there's the cdc study on masking from May 2020 that looked at studies on mask efficacy from studies performed from 1948 through 2018. That study concluded in a community setting cloth masks likely did nothing because in community settings proper mask usage is not likely to occur and touching ones face, adjusting the mask and not changing the mask after a couple hours of use you were likely to increase transmission.
The cdc also had another study on masking in schools in GA, which compared school districts with mask mandates versus those that didn't and found mask mandates on kids did nothing to curb transmission rates. It did find that adults and teachers masking in schools had some impact, but not kids.
At this point in the pandemic there is little quality (key word: quality) evidence to support ongoing masking beyond respirators.
Anecdotal, but yesterday we took my daughter to Disney on ice. The clown mayor of Columbus, OH put a mask mandate in place and the arena enforced it at the door. But after that people had their masks down and off. During the show 2/3 of people weren't wearing masks at all. Masks at this point are cosmetic theater.
Johns Hopkins just released a study saying lockdowns only reduced mortality by 0.2%. I admittedly haven't read the studies that support or challenge the value of lockdowns, but at face value this would imply there are still questions the value of lockdowns.
Cdc study may 2020:
https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article
Bangledesh mask study:
https://www.science.org/doi/10.1126/science.abi9069
critique of Arizona mask study:
https://www.theatlantic.com/science/archive/2021/12/mask-guidelines-cdc-walensky/621035/
Critique of Georgia mask study:
https://nymag.com/intelligencer/2021/08/the-science-of-masking-kids-at-school-remains-uncertain.html
Johns Hopkins Study:
https://www.webmd.com/lung/news/20220204/lockdowns-covid-deaths-study