Universal mask requirements are protective against Delta variant in schools. Universal mask requirements in schools protected students and staff from COVID-19 during the Delta variant surge in late 2021. Two recent studies found that universal masking led to fewer COVID-19 infections in schools than optional masking policies. According to an analysis conducted by the Centers for Disease Control and Prevention (CDC) and published in the March 11 Morbidity and Mortality Weekly Report, public school districts in Arkansas with universal mask requirements had 23% fewer COVID-19 cases among students and staff during August-October 2021 than districts without mask requirements. A larger study published online on March 9 in Pediatrics analyzed data on over 1 million students and 157,000 staff in 61 schools across nine states. The researchers found that schools with optional masking polices had 3.6 times the rate of secondary transmission of COVID-19 as schools with universal masking policies. Authors of the CDC report note that "masks remain an important part of a multicomponent approach to prevent COVID-19 in K-12 settings."