The Study That Convinced the CDC To Support Mask Mandates in Schools Is Junk Science

By Robby Soave of Reason. Excerpt:

"On September 28, Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky shared the results of a new study that appeared to confirm the need for mask mandates in schools. The study was conducted in Arizona over the summer, and published by the CDC's Morbidity and Mortality Weekly Report: It found that schools in counties without mask mandates had 3.5 times more outbreaks than schools in counties with mask mandates.

The significance of that finding should have raised eyebrows, according to The Atlantic's David Zweig. "A number of the experts interviewed for this article said the size of the effect should have caused everyone involved in preparing, publishing, and publicizing the paper to tap the brakes," he wrote in a new article that explores the study's significant flaws. "Instead, they hit the gas."

His article demonstrates quite convincingly that the study's results are suspect:

But the Arizona study at the center of the CDC's back-to-school blitz turns out to have been profoundly misleading. "You can't learn anything about the effects of school mask mandates from this study," Jonathan Ketcham, a public-health economist at Arizona State University, told me. His view echoed the assessment of eight other experts who reviewed the research, and with whom I spoke for this article. Masks may well help prevent the spread of COVID, some of these experts told me, and there may well be contexts in which they should be required in schools. But the data being touted by the CDC—which showed a dramatic more-than-tripling of risk for unmasked students—ought to be excluded from this debate. The Arizona study's lead authors stand by their work, and so does the CDC. But the critics were forthright in their harsh assessments. Noah Haber, an interdisciplinary scientist and a co-author of a systematic review of COVID-19 mitigation policies, called the research "so unreliable that it probably should not have been entered into the public discourse."

It turns out that there were numerous problems with the study. Many of the schools that comprise its data set weren't even open at the time the study was completed; it counted outbreaks instead of cases; it did not control for vaccination status; it included schools that didn't fit the criteria. For these and other reasons, Zweig argues that the study ought to be ignored entirely: Masking in schools may or may not be a good idea, but this study doesn't help answer the question. Any public official—including and especially Walensky—who purports to follow the science should toss this one in the trash."