Pima County co-authored a study published Sept. 24, 2021, by the Centers for Disease Control and Prevention (CDC) that shows
universal mask wearing in Arizona K-12 schools considerably reduces the likelihood of a school-associated COVID-19 outbreak.
The investigation included 999 K–12 public non-charter schools in Pima and Maricopa counties, finding that schools without a mask requirement were 3.5 times more likely to experience a COVID-19 outbreak.
Pima County Health Department Director Dr. Theresa Cullen and the department's Schools COVID-19 liaison Brian Eller were among seven authors in the study, led by Arizona State University.
"The findings reinforce and give credence to the existing guidance from the CDC and Pima County: Universal mask wearing in schools is absolutely an essential part of a layered mitigation strategy against the spread of COVID-19," Cullen said.
Mask policies and school-associated outbreaks in nearly 1,000 schools were included in this study during the period of July 15 to August 31, 2021.
Schools with mask requirements were categorized as having early mask requirements if the mandate was in place at the start of the school year, or late mask requirements if the mandate was initiated after the start of the school year. Of 191 school-associated outbreaks, 8.4 percent occurred in early mask requirement schools, 32.5 percent in late mask requirement schools, and 59.2 percent in schools without a mask requirement.
A school-associated outbreak was defined as the occurrence of two or more laboratory-confirmed COVID-19 cases among students or staff members at the school within a 14-day period and at least seven calendar days after school started.
The Pima County Health Department (PCHD) has and continues to work closely with all county K-12 schools -- public, charter, and private -- assisting in COVID-19 mitigation, testing and vaccinations. PCHD continues to support CDC guidelines, which recommend that K-12 schools implement universal indoor masking as part of a layered prevention strategy.