CDC
@CDCgov
New @CDCMMWR shows counties w/ school mask requirements had a smaller increase in pediatric #COVID19 case rates than counties w/o school mask requirements. #MaskUp in schools to help control the spread of COVID-19 in children and adolescents. http://bit.ly/MMWR92421c
2:55 PM · Sep 24, 2021 //

Notice the massaging being done to the language in this announcement. It doesn’t actually say schools with mask mandates show a smaller increase in pediatric COVID-19 case rates. Rather, it says “counties,” and we’ll get to why that is in a minute. Further, the CDC absconds from including in their graphic the actual, numerical difference being touted.

For posterity, here’s the link to the full study so you can see exactly what it actually covers.

https://www.cdc.gov/mmwr/volumes/70/wr/mm7039e3.htm?s_cid=mm7039e3_w

In short, what we have is a “study” that didn’t even cover a period where children were in school — save for a week or so. The “study” is also based on a data set of counties that do not control for prior infection rates, testing capacity, etc. in order to conduct a valid comparison between areas that have school mask mandates and ones that don’t. And even still, they came up with a result that shows almost no difference in the real number of cases.

Lastly, just to put a fine point on all this, the CDC’s own study admits that it’s ecological and should not be used to assign causation in regards to masks and infection rates. They also admit a lack of control regarding several other key variables.