Schools that required masks, improved ventilation reported fewer COVID-19 cases: CDC study

Schools in Georgia that required teachers and staff to wear masks and improved ventilation reported fewer COVID-19 cases, according to a Centers for Disease Control and Prevention (CDC) study released on Friday.

The research, conducted by the CDC and the Georgia Department of Public Health, determined that COVID-19 incidence was 37 percent lower in schools that mandated masks for teachers and staff. Schools that implemented at least one ventilation strategy saw a 39 percent reduction in coronavirus cases among students and staff.

The ventilation improvements ranged from dilution methods, which refer to running fans and keeping doors and windows open, to filtration with or without purification. Schools that used dilution methods saw 35 percent less COVID-19 incidence, and others that used dilution and filtration methods together saw 48 percent fewer cases. 

The schools that mandated mask wearing for students reported a 21 percent lower COVID-19 incidence rate — a figure not considered statistically significant — which researchers speculated could have been because of “differences in mask-wearing behavior among students in schools with optional requirements.”

The study involved 169 elementary schools across 51 counties that opened for in-person instruction in fall 2020 and spanned 26 days in November and December. Researchers calculated that there were 3.08 cases among students and staff per 500 enrolled students in that period. 

The CDC noted there were no previous U.S. studies analyzing COVID-19 cases in schools with different precautions, including mask requirements and ventilation efforts. 

The agency said it recommends schools institute “multiple prevention strategies,” including masking, better ventilation, social distancing and contact tracing.

Schools have been under growing pressure to fully reopen for in-person instruction as the Food and Drug Administration (FDA) gave an emergency authorization to the Pfizer-BioNTech vaccine for 12- to 15-year-olds last week. 

More than half of U.S. schools, 51 percent, are operating fully in-person as of May 10, while 48 percent are conducting hybrid programs and 1 percent are fully remote, according to the Return to Learn Tracker.  

The CDC also announced new mask guidance last week that allows fully vaccinated people to remove their masks in most indoor and outdoor settings. But the agency clarified that it recommended universal mask wearing in schools for adults and children because most children have not yet been vaccinated. 

The American Federation of Teachers president called on the agency to provide further information and to clear up recommendations on masking for various educational scenarios.