Margery Smelkinson, Leslie Bienen, and Jeanne Noble

But in America about half of the country’s 53 million children remain compulsorily masked in school for the indefinite future. Sixteen U.S. states and the District of Columbia follow the CDC guidance closely and require masks for students of all ages, regardless of vaccination status; other states rely on a patchwork of policies, usually leaving decisions up to local school districts. (Nine states have banned school mask mandates, though in five of them, lawsuits have delayed implementation of the ban.) Many deep-blue areas such as Portland, Oregon; Los Angeles; and New York City have gone beyond CDC guidance and are masking students outdoors at recess, in part because of byzantine rules that require an unmasked “exposed” student to miss multiple days of school, even if the putative exposure is outside.

Read: The CDC’s flawed case for wearing masks in school

Many public-health experts maintain that masks worn correctly are essential to reducing the spread of COVID-19. However, there’s reason to doubt that kids can pull off mask-wearing “correctly.” We reviewed a variety of studies—some conducted by the CDC itself, some cited by the CDC as evidence of masking effectiveness in a school setting, and others touted by media to the same end—to try to find evidence that would justify the CDC’s no-end-in-sight mask guidance for the very-low-risk pediatric population, particularly post-vaccination. We came up empty-handed.

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.