BOSTON (AP) — Many Massachusetts school children who returned to the classroom Monday after a weeklong vacation were no longer required to wear face coverings indoors.

Gov. Charlie Baker and state Education Commissioner Jeffrey Riley announced early in February that they were lifting the statewide indoor mask mandate effective Monday and would instead leave masking requirements up to individual school districts.

Some districts, including in the state’s largest cities of Boston, Worcester and Springfield, have decided to keep indoor mask mandates for students and staff in place for the time being.

Boston will reassess masking rules based on COVID-19 metrics, Mayor Michelle Wu has said.

Worcester’s Board of Health has a meeting scheduled for March 7 to weigh masking requirements, and the city’s School Committee has said it will follow the health board’s recommendations.

Students and staff have been required to wear masks for the entire school year. Riley implemented the mask requirement in August to stem the spread of the coronavirus, and it was extended several times — most recently in early January, when the highly contagious omicron variant was surging.

Several dozen schools had been allowed to drop mask requirements if they reached an 80% vaccination threshold among staff and students.

Masks are still required on school buses and other official school transportation, because that is a federal regulation.

Riley had said he was lifting mask requirements because of the state’s high vaccination rates among children and in consultation with public health experts.

Many cities and towns have also been lifting mask mandates for all indoor public spaces as new cases of the coronavirus wane.