Counties that do not require face masks in K-12 schools have seen a sharper increase in child COVID cases than those that do have a face mask mandate in schools.
That's according to a study released Friday by the Centers for Disease Control and Prevention (CDC), which looked at how pediatric COVID cases in counties with and without school mask mandates changed over the opening weeks of the school year.
Child COVID cases rose across the board. But those counties that did not implement a school masking requirement "experienced larger increases in pediatric COVID-19 case rates" compared to those with a mask mandate.
The counties with a K-12 mask mandate saw, on average, 16.32 child COVID cases per 100,000 children each day. Those without any face covering mandate saw an average of 34.85 such cases per 100,000 children daily. The study ultimately included 520 counties, about 62% of which did not have a mask requirement.
The study only looked at counties with no conflicting school requirements. So if a county was home to some schools with a mask requirement and some schools without a mask requirement, researchers simply excluded it from the analysis.
The researchers noted a few limitations. Because this was an observational study, there cannot be any conclusions made about causation. And the case rates included all children under the age of 18 in each county not the rate just among the school-aged population.
It's possible that the disparity in COVID cases between mask-wearing and non-mask wearing schools could also be down to vaccination rates among 12-17 year olds in the counties observed.
Nonetheless, the study still calls masking "a critical strategy for preventing the transmission" of COVID in schools.
Here in Minnesota, 95 schools over the past two weeks have recorded at least five positive COVID cases among students and staff. Overall K-12 case numbers are also rising, with 859 infections as of the week ending Sept. 18, up from 820 infections the week before.