These findings cast doubt on the impact of many of the most common mitigation measures in American schools. Distancing, hybrid models, classroom barriers, HEPA filters, and, most notably, requiring student masking were each found to not have a statistically significant benefit. In other words, these measures could not be said to be effective.
In the realm of science and public-health policy outside the U.S., the implications of these particular findings are not exactly controversial. Many of America’s peer nations around the world — including the U.K., Ireland, all of Scandinavia, France, the Netherlands, Switzerland, and Italy — have exempted kids, with varying age cutoffs, from wearing masks in classrooms. Conspicuously, there’s no evidence of more outbreaks in schools in those countries relative to schools in the U.S., where the solid majority of kids wore masks for an entire academic year and will continue to do so for the foreseeable future. These countries, along with the World Health Organization, whose child-masking guidance differs substantially from the CDC’s recommendations, have explicitly recognized that the decision to mask students carries with it potential academic and social harms for children and may lack a clear benefit.