(ABC 4)- A study of Arizona K-12 schools by the Centers of Disease Control and Prevention found that schools without a mask mandate had 3.5 times as many outbreaks as schools that mandated them.

The study published September 24 looked at data from 999 eligible public schools in Maricopa and Pima counties in Arizona. Out of those eligible schools, 21%, or 210 schools had an early mask requirement, 309 schools enacted a late mask requirement 15 days after the school year started, and 480 schools had no mask requirements. 

From the period of July 15 to August 31, 2021, outbreaks of Covid-19 occurred in 191 schools. Out of those schools, 8% had early mask requirements, 32.5% enacted late mask requirements, and 59.2% had no mask requirements. 

“The odds of a school-associated COVID-19 outbreak in schools without a mask requirement were 3.5 times higher than those in schools with an early mask requirement,” the CDC report said.

The report also said that although the CDC recommends universal indoor masking in K-12 schools, those requirements can vary by school district, county, and state. 

Due to the high level of transmission of the Delta variant of the SARS-Cov-2 virus, masking along with vaccination of eligible students, staff members and faculty “remains essential to COVID-19 prevention in K–12 settings,” the CDC added in the report.