The study, which followed Boston-area schools during the 2021-22 school year, found that ending mask requirements was associated with 45 additional cases of covid-19 per 1,000 students and members. personnel – nearly 12,000 cases over a 15-year period. weekday period from March to June.
School systems in Boston and Chelsea, Mass., remained with universal masking even after Massachusetts officials rescinded the statewide requirement in February. But 70 neighboring school districts have removed the masking mandates.
Prior to this split, covid trends were similar across all school districts. Thereafter, they diverged, with a “significantly higher incidence seen in school districts that lifted masking requirements,” according to the research.
“Our results support universal masking as an important strategy for reducing the incidence of covid-19 in schools and the loss of in-person school days,” wrote the authors, who included researchers from the University of Harvard, Boston University and the Boston Public Health Commission.
The toll of additional covid cases was stark: they resulted in at least 17,500 missed school days for pupils and 6,500 missed school days for staff, at a time when schools were following a period of isolation of at least five days for those infected, the study said.
Universal masking helped the most when virus levels were highest, suggesting the safety measure is most useful just before or during periods of high transmission. Massachusetts was one of 18 states with a masking requirement in place for public schools in 2021-22. He withdrew the policy when guidelines changed from the Centers for Disease Control and Prevention.
Meagan Fitzpatrick, an epidemiologist and infectious disease transmission modeler at the University of Maryland School of Medicine, called the study well-designed and well-executed, saying she wished there had been one. like this one earlier in the pandemic.
“The difference in COVID risk between districts with and without masking is striking,” she wrote in an email. On the contrary, she said, the study underestimates the ability of masks to control the disease, because even in schools without mandates, some students and staff likely continued to wear masks.
The findings support access and exit ramps for mask mandates, she said, which “makes sense, because masking does the most good when there’s disease to prevent.”
School districts that continued with blackout mandates had higher percentages of students of color, students from low-income backgrounds, students with disabilities and English language learners, the study found. They also tended to have older buildings, with outdated or missing ventilation and filtration systems and larger classrooms.
Jennifer Kates, senior vice president of KFF, a health-focused nonprofit, which helped lead its covid work, said the study demonstrated a “significant” effect of universal masking. – a discovery that could be useful in efforts to control a future variant of covid or another infectious disease. “This is a very inexpensive and very effective intervention,” she said.
Fitzpatrick said the finding is significant for the current child health crisis, given that many hospitals are overwhelmed with children with respiratory infections, including RSV, influenza and covid. “Masking is one of the few tools that can combat all of this,” she said.