(CBS/CNN) — The US Centers for Disease Control and Prevention updated its physical distancing guidelines for children in schools from 6 feet to 3 feet Friday.

The CDC has previously said schools should try to maintain at least 6 feet of distance between children, but in light of new data, the agency is now recommending most students maintain at least 3 feet of distance.

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study led by Beth Israel Deaconess Medical Center in Boston released earlier this month compared Massachusetts classrooms that spaced masked students three feet apart and six feet apart.

The study, recently published in the journal Clinical Infectious Diseases, found there was no difference in COVID-19 rates between Massachusetts schools that mandated 3 feet of physical distance compared to 6 feet, as long as everyone wore masks.

The CDC’s new guidance is not expected to have an impact in Massachusetts, which has been telling school districts they only need to provide three feet of space. The state plans to bring students back to full in-person learning next month.

On Friday, the CDC released three new studies it says support distancing of 3 feet between students, so long as everyone is wearing a mask and other prevention measures are in place.

CDC director Dr. Rochelle Walensky said Thursday that the issue is urgent.

“Indeed, because six feet has been such a challenge there, science has leaned in and there are now emerging studies on the question between three feet and six feet,” Walensky told Sen. Susan Collins during a hearing of the Senate Health, Education, Labor and Pensions Committee.

What’s in the CDC guidance

As always, masks are key. At times when it’s not possible to accommodate masks, like when eating, CDC says six feet of distance should be maintained.

The agency recommends keeping student and teachers in distinct groups, or cohorts, throughout the day and maintaining 6 feet of distance between those groups, when possible. In middle schools and high schools where community transmission is high, CDC advises students to stay 6 feet apart, if cohorting is not possible.

CDC also recommends 6 feet of distance in common areas, like lobbies and auditoriums, and during activities like singing, shouting, band or sport practices. They say it’s better to move those kinds of activities, where increased exhalation occurs, outdoors or to well-ventilated spaces.

In classrooms, CDC says layout changes, like removing nonessential furniture and facing desks in the same direction, can help maximize distance between students. On school buses, the agency recommends seating students one child per row, skipping rows and opening windows to increase ventilation.

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When it comes to adults, including teachers and staff, the agency says its better to stick to 6 feet of distance, both with other adults and with children.

“Several studies have found that transmission between staff is more common than transmission between students and staff, and among students, in schools,” the agency notes.

CDC advises limiting interaction among teachers and staff during meetings and breaks.

Layers of protection

For schools returning to the classroom, it’s important to implement layers of safety precautions, so if one fails, another will provide some protection, said Dr. Naomi Bardach, the lead for California Health and Human Services’ school reopening plan.

She said the updated guidance will give schools more options.

CDC says COVID-19 testing can provide additional protection for sports and in schools that use less than 6 feet of distancing between students in classrooms.

“You have to always be thinking about the layers in place,” said Bardach. “What are those other layers? It’s the masking, it’s the ventilation, hand hygiene, symptom screening and then exposure screening. It’s thinking about all those layers together.”

Dr. Ebbing Lautenbach, chief of the Infectious Diseases Division at the University of Pennsylvania’s Perelman School of Medicine, told CNN that the new CDC guidance should make it easier for schools to return to full time in-person teaching as opposed to staggered school attendance.

“Getting kids back into in-person learning is very difficult logistically from a space standpoint if you have to keep them 6 feet apart, so if the guidance is changed to 3 feet, it will make things much more feasible to get kids back into in-person classroom learning,” Lautenbach said.

He warned, however, the key assumption to the updated physical distancing recommendation is that all students and teachers are wearing appropriate facial coverings.

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(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. CNN’s Lauren Mascarenhas contributed to this report.)