Thread by @kerpen

Thanks for this @LeadStoriesCom. They found what I missed on July 9 -- a separate "science brief" page on the CDC site that tried to justify masking. Let's look. leadstories.com/hoax-alert/202…

First four and last cannot find any mask effect because they lack controls. Swiss study shows success (unmentioned by CDC) with no masking under age 12, and masking "in open spaces" age 12+.
ncbi.nlm.nih.gov/pmc/articles/P…

The German claim is interesting but the difference is small "containment measures implemented in schools may have some protective effect." Can't isolate mask effect. Conclusion is that well-designed evaluations are needed? Did that happen? eurosurveillance.org/content/10.280…

The distancing section has this 1 meter success story. CDC does not note that Norway recommends against masking elementary students

This (in the distancing, not masks) section is the first real citation to support student masking. The Florida MMWR. But why use the MMWR that was based on reopening plans and only 2020 data, confounded by different start dates?

We have better data now and it shows that the lowest case rates in Florida schools were in counties that mandated masks on teachers but were *optional for students.*

https://twitter.com/kerpen/status/1395790011551862792

Interestingly, the conclusion was similar in the CDC's own most recent masking study.

The Georgia MMWR, comparing masked to mask-optional schools, which found teacher masking had a statistically significant effect but student masking did not.
cdc.gov/mmwr/volumes/7…

The CDC's own most recent and on-point study on school masking doesn't warrant a mention in its own "science brief"? That seems odd.

Reminder: CDC's "science brief" on its school guidance has only one study that compares mask-mandate to mask-optional schools, and it's an outdated, confounded first-semester only study. They ignore their own most relevant study, which found no statistically significant effect.