A recent publication in Pediatrics demonstrated the benefits of mandatory masking in schools during the period of exposure to Delta strain SARS-CoV-2 virus. The study included 61 school districts with classes ranging from kindergarten through grade-12 incorporating data from late July 2021 through mid-December 2021.  The study included a population of 1.1 million students and 157,000 staff in nine states distributed across the U.S.  The study was supported by the NIH Rapid Acceleration of Diagnostics program and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. 

The study determined that school districts that mandated masking recorded an incidence rate of 7.3 cases of in-school infection per 100,000 compared to school districts with optional masking where the rate was 26.4 cases per 100,000. Mandatory masking attributed to a 72 percent reduction of in-school COVID cases compared to districts with optional masking.  It was calculated that ten percent of all cases of COVID diagnosed were acquired through attending school.

The conclusions derived from the school study can be applied to plant situations where workers are in close proximity. Fortunately with higher levels of immunity from complete vaccination (two primers and a booster) and a decline in incidence of infection attributed to the Omicron strain, mask requirements are understandably now being relaxed. Should a new variant of SARS-CoV-2 emerge the school study that demonstrated the value of masking under close contact situations to reduce incidence of COVID could be used to justify masking in specific situations.