The Atlantic published a piece today about the CDC’s school masking policy. There are three authors of the piece including an infectious-disease scientist, a veterinarian and a emergency room doctor. All three looked at the literature surrounding school masking and found it insufficient to justify the current CDC guidance.

To our knowledge, the CDC has performed three studies to determine whether masking children in school reduces COVID-19 transmission. The first is a study of elementary schools in Georgia, conducted before vaccines became available, which found that masking teachers was associated with a statistically significant decrease in COVID-19 transmission, but masking students was not—a finding that the CDC’s masking guidelines do not account for.

The second study, with the most dramatic findings by far, was examined in a previous piece in the Atlantic. That study had several serious problems which caused one reviewer to suggest it “probably should not have been entered into the public discourse.”

The third CDC study found that U.S. counties without mask mandates saw larger increases in pediatric COVID-19 cases after schools opened, but again did not control for important differences in vaccination rates. The CDC has cited several other studies conducted in the previous school year to support its claim that masks are a key school-safety measure. However, none of these studies, including ones conducted in North Carolina, Utah, Wisconsin, and Missouri, isolated the impact of masks specifically, because all students were required to mask and no comparisons were made with schools that did not require masks.

Therefore, the overall takeaway from these studies—that schools with mask mandates have lower COVID-19 transmission rates than schools without mask mandates—is not justified by the data that have been gathered. In two of these studies, this conclusion is undercut by the fact that background vaccination rates, both of staff and of the surrounding community, were not controlled for or taken into consideration…

To justify mask requirements in school at this point, health officials should be able to muster solid evidence from randomized trials of masking in children. To date, however, only two randomized trials have measured the impact of masks on COVID transmission. The first was conducted in Denmark in the spring of 2020 and found no significant effect of masks on reducing COVID-19 transmission. The second is a much-covered study conducted in Bangladesh that reported that surgical masks (but not cloth) were modestly effective at reducing rates of symptomatic infection. However, neither of these studies included children, let alone vaccinated children.

I wrote about the Bangladesh study here and it found that surgical masks (not cloth masks) reduced the spread of the virus 11 percent, but the effectiveness of cloth masks in reducing the spread was somewhere between 11 percent and zero. Obviously if cloth masks made little or no difference in protecting people from the delta variant, it’s even less likely to protect them from the highly transmissible omicron variant. That’s why some schools are now requiring students to wear surgical or N95 masks instead. For instance:

The Los Angeles Unified School District is prohibiting students from wearing only cloth face masks on campus as the country grapples with a continued surge of COVID-19 infections driven by the omicron variant.

The district announced updated guidance on Friday requiring students to wear “well-fitting, non-cloth masks with a nose wire” both indoors and outdoors. Employees will have to wear surgical grade masks or higher…

According to public health experts, the cloth masks common at the beginning of the pandemic may no longer be enough to prevent you from catching the highly contagious omicron variant. Instead, officials recommend an N95 or a similar high-filtration respirator for increased protection from the virus.

But again, there are no studies showing surgical masks reduce the spread of omicron in schools. The Atlantic piece concludes with this statement: “Imposing on millions of children an intervention that provides little discernible benefit, on the grounds that we have not yet gathered solid evidence of its negative effects, violates the most basic tenet of medicine: First, do no harm.”