Schools without mask mandates are more likely to have COVID-19 outbreaks, CDC finds

The Centers for Disease Control and Prevention released new studies Friday that show enforcing masks in schools helps reduce the spread of COVID-19. 

One study looked at data from schools in Arizona's Maricopa and Pima Counties after they resumed in-person learning in late July for the 2021-22 academic year. The two counties account for roughly 75% of the state's population. 

The CDC found that the K-12 schools that did not have mask requirements at the beginning of the school year were 3.5 times more likely to have COVID outbreaks than schools that required all people, regardless of vaccination status, to wear a mask indoors from the first day of school.