New study based on Mass. schools finds masks protected students, staff from COVID-19

Kindergarteners wearing masks worked on an assignment in February in Everett, before masking became optional.Jessica Rinaldi/Globe Staff

A study comparing the experience of Massachusetts schools that maintained masking requirements early this year with those that dropped them has provided new evidence that masks are beneficial in protecting students and staff from COVID-19.

The preprint study, which has not been peer-reviewed, was authored by researchers from the Harvard T.H. Chan School of Public Health, Boston University School of Public Health, and the Boston Public Health Commission.

“Masking is a relatively low-cost but effective intervention that can protect students and staff from substantial illness and loss of in-person days in school,” the study said.

“Despite compelling evidence that masking significantly reduces the spread of SARS-CoV-2, political will and public adherence to masking has waned,” the study said. “Our study confirms that universal masking requirements can benefit all students and staff, and therefore represents an important strategy to mitigate the impacts of structural racism, ensure health equity, and to avoid potential deepening of educational inequities.”

The study’s lead author, Tori Cowger, a postdoctoral fellow at the FXB Center for Health and Human Rights at Harvard’s Chan School, said: “The big takeaway from this study is that universal masking policies in schools remain an important policy tool, among other mitigation measures, to consider during times of high community transmission.”

Noting that it’s almost time for children to go back to school, Eleanor Murray, an assistant professor at BU’s School of Public Health who was one of the coauthors, tweeted Wednesday: “How do we stop COVID from going back to school too? Our new pre-print confirms face masks must be part of our plan!”

It's almost Back to School time & we're still seeing about 100k cases a day here in the US.

How do we stop COVID from going back to school too?

Our new pre-print confirms face masks must be part of our plan!

Let me explain /🧵https://t.co/iS5NPvoC9H

— Dr Ellie Murray, ScD (@EpiEllie) August 10, 2022

Eastern Massachusetts school districts that removed mask requirements “saw a *dramatic increase* in COVID cases compared to if those districts had retained mask requirements. And this was *despite* all other mitigation efforts those districts did,” Murray tweeted.

In February 2022, after the statewide school masking mandate was rescinded, only Boston and Chelsea out of 79 school districts in Greater Boston, maintained masking requirements in their schools, the study said. That gave researchers an opportunity to examine the impact of the removal of masks on COVID-19 case rates among students and staff.

Researchers said their observational study found that dropping mask mandates was associated with an additional 44.9 COVID-19 cases per 1,000 students and staff over 15 weeks after the lifting of the statewide school masking requirement.

The researchers said that represented nearly 30 percent of all cases observed in schools during that time.

Murray said on Twitter it added up to an estimated 11,901 extra cases, and that meant thousands of lost days for both students and teachers and other staff.

“This study is further proof that masking is highly effective at preventing COVID-19 transmission in indoor settings. As we adjust to living with COVID-19, masking will continue to be an important strategy for decreasing person to person transmission, and one that should be considered during periods of high community spread,” Dr. Bisola Ojikutu, executive director of the Boston Public Health Commission, said in a statement.