On Mar. 10, 2022, schools with mandatory masking during the Delta surge had approximately 72% fewer cases of in-school transmission of SARS-CoV-2 when compared to schools with optional or partial masking policies, according to a study funded by the National Institutes of Health (NIH).

The study included more than 1.1 million students and over 157,000 staff attending in-person school across nine states: North Carolina, Wisconsin, Missouri, California, Washington, Georgia, Tennessee, Kansas and Texas. The study was supported by NIH’s Rapid Acceleration of Diagnostics – Underserved Populations program and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The study was published in Pediatrics.