Boston Public Schools students will be required to wear masks in the fall, Acting Mayor Kim Janey said Thursday, pointing to the fact that school-age children under the age of 12 are still ineligible for the vaccine.

“As folks know, there are a number of children who still are not eligible for the vaccine,” Janey said, “and so children are currently wearing masks as they are in summer school and in different programs throughout the city. And in this fall, they will be wearing masks still.”

The announcement came on the same day that Gov. Charlie Baker said there were no plans to implement a mask mandate in schools at the state level. Democratic state lawmakers urged the governor to reinstate the mask rule to protect children from rising case counts in a letter Wednesday, noting that such a policy could be revisited once children are able to receive the vaccine.

“We don’t have plans to change our current policies with respect to our schools in the fall,” Baker said at a grant funding awards event Thursday. “What’s gotta be the rule of thumb here is that people make decisions based on the current state of play with respect to the virus in their states — and we’re in a very different place than most other parts of the country.”

Janey made the announcement when she took questions at the swearing-in ceremony for two new Boston School Committee members.

The Boston Teachers Union stated its support for the mandate, adding that it would be open to re-evaluating whether it was necessary if and when COVID-19 vaccines become available for children under 12.

“This is not actually even just about the students or our vulnerable students, but it's also about vulnerable family members who live with their students and the safety of the larger community,” BTU President Jessica Tang told GBH News. “As much as it may be an inconvenience, to protect everyone, I do think it's the right thing to do.”

The American Academy of Pediatrics updated its guidance Monday to recommend that everyone in schools above the age of two — whether vaccinated or not — wear masks in the fall to stem the transmission of COVID-19.

Though Massachusetts has the second-highest adult vaccination rate in the country, with 74% fully vaccinated as of Thursday, COVID-19 cases have been rising in recent weeks from record lows in late June.

GBH News reporter Esteban Bustillos contributed reporting.