Do masks reduce transmission of the coronavirus in school? Syndicated columnist Jacob Sullum says there is little evidence they do:
Supporters of school mask mandates assume they are effective at reducing COVID-19 transmission, then desperately search for evidence to validate that conviction….The Centers for Disease Control and Prevention (CDC) began recommending “universal masking” in schools a year ago. At that point, there was no solid empirical basis for the CDC’s advice, and that is still true. Most of the studies cited by the CDC did not even compare schools with mask mandates to schools without them. One exception was a study of Georgia elementary schools published last May, which found that masking of teachers was associated with a statistically significant reduction in COVID-19 transmission, but masking of students was not. A subsequent study, reported last September, found that “counties without school mask requirements experienced larger increases in pediatric COVID-19 case rates after the start of school compared with counties that had school mask requirements.” But that study did not take into account vaccination rates or other COVID-19 safeguards, both of which are potentially important confounding variables. Since “this was an ecologic study,” the researchers noted, “causation cannot be inferred.”
Another study published the same day found that COVID-19 outbreaks were more common in Arizona schools that did not require masks. Again, that study did not control for vaccination rates or other mitigation measures, and critics pointed out various other weaknesses. “You can’t learn anything about the effects of school mask mandates from this study,” Arizona State public health economist Jonathan Ketcham told science writer David Zweig. Noah Haber, a Stanford postdoctoral fellow who had co-authored a systematic review of research on COVID-19 mitigation measures, described the study as “so unreliable that it probably should not have been entered into the public discourse.”… Data from Florida, Tennessee, North Dakota, Texas, the U.K., and Spain suggest [mask mandates] are not [necessary for schools to operate safely]. A randomized trial in Bangladesh found that surgical masks reduced COVID-19 cases by 11 percent, but cloth masks—the kind most commonly used in schools—did not have a statistically significant effect….the theoretical, unsubstantiated benefits of school mask mandates have to be weighed against the burdens they impose, which include interference with communication, learning, and social interaction…That calculus should take into account the vanishingly low COVID-19 fatality rate among children (about 0.002 percent, according to the CDC); vaccines and treatments that dramatically reduce the risk of severe symptoms; and the availability of high-quality masks that immunocompromised children and adults can use to protect themselves from infection.