Student quarantines after masked exposure do not affect transmission, study finds

Study results from a large Nebraska school district demonstrated that eliminating student quarantines after mask-on-mask COVID-19 exposure was not associated with secondary transmission, researchers reported in Pediatrics.

“With essentially all students returning to in-person learning and increased vaccination rates among staff and adolescents, our study and others suggest that student quarantines after mask-on-mask exposure do not have a detectable impact on secondary transmission but substantially decrease in-person learning time,” Angelique E. Boutzoukas, MD, a first-year fellow in the department of pediatrics at the Duke University School of Medicine, and colleagues wrote.

“The prompt elimination of unnecessary quarantines may facilitate recovery from the emotional and academic losses accrued by U.S. children during the 2020-2021 school year,” they wrote.

The observational study was conducted in a K-12 public school district in Omaha, Nebraska, from Aug. 1, 2020, to March 15, 2021. It included more than 23,000 students and 2,855 staff members at 25 elementary schools, six middle schools, four high schools and one young adult program.

“We assessed primary and secondary COVID-19 infections in teachers and staff, frequency of quarantine for students and staff, and the impact of eliminating quarantine on secondary transmission in mask-on-mask exposure settings,” Boutzoukas and colleagues wrote.

The district’s schools opened for in-person learning on Aug. 10, 2020, with students given an option of either full-time in-person or remote education. All schools included mitigation strategies, including 3-foot distancing in classrooms, mandated masking for all students and staff and daily symptom screenings, although there was limited ability to open windows within the classrooms and no changes were made to the ventilation systems, the researchers said.

Further, any student or staff member with symptoms consistent with COVID-19 required a negative test result before being allowed back into the district, with all confirmed cases initially requiring a 14-day isolation. In November, isolation was reduced to 10 days if the case patient was fever free.

“On Sept. 21, 2020, an updated Directed Health Measure issued by the Nebraska Department of Health and Human Services (NDHHS) allowed masked students exposed to masked COVID-19-positive persons (students or staff) in school (referred to as mask-on-mask exposure) to avoid quarantine,” they wrote.

“This elimination of quarantine for mask-on-mask exposure did not apply to students who had unmasked school exposures or any community exposure, nor did this apply to K–12 staff (regardless of masked or unmasked exposure) who continued to quarantine for standard periods per health department and CDC recommendations.”

On Dec. 2, 2020, after the CDC updated its recommendations, the NDHHS issued an updated health measure, which allowed quarantined staff and students to return to school on day 8 after a negative COVID-19 test. This remained in place until the study’s end on March 15, 2021.

Ultimately, the researchers found that the quarantine did not provide benefits against secondary transmission.

“The district implemented a policy in September 2020 allowing in-person learning after close contact to COVID-19-infected persons in the mask-on-mask K–12 setting,” they wrote. “There was a notable decrease in required quarantines, considering the number of primary infections coming into the school between the fall and spring portions of our study. In the fall, for every primary infection in a student, four times the number of children were quarantined, and only two within-school transmissions occurred.

“In the spring semester, the [number] of students quarantined per primary infection in students was 41% lower than that in the fall semester, and there was no known secondary transmission in close contacts who qualified to avoid quarantine.”