Massachusetts boasts a high vaccination rate — about 63 percent of residents — and lower rates of infection than many other locations in the country. However, cases are rising here, with clusters in some communities, such as Provincetown, where an outbreak has infected more than 800 people since the Fourth of July holiday.

And, on Tuesday, the Centers for Disease Control and Prevention included five Eastern Massachusetts counties among the places in the United States where people, including those who have been vaccinated, should wear masks in indoor public spaces because of a heightened risk of transmission.

New data suggest vaccinated people can spread the virus, the CDC said.

Biden is expected to announce Thursday that all civilian federal employees will be required to be vaccinated or face regular virus testing. In New York, where infections have grown by 150 percent and hospitalizations have climbed 69 percent over the past two weeks, Governor Andrew M. Cuomo announced that state employees there would be required to be vaccinated or routinely tested.

“It’s smart, it’s fair, and it’s in everyone’s interest,” Cuomo said during a luncheon hosted by a New York civic group.

In New England, Maine Governor Janet T. Mills said Wednesday that her state will recommend people wear face coverings in indoors spaces in high-risk areas for COVID-19 transmission, regardless of vaccination status. Mills’s office noted that the CDC now considers York and Piscataquis counties to have “substantial” levels of community transmission.

Baker said his administration is reviewing the CDC guidance and consulting with experts before making any policy changes, but he ruled out instituting travel restrictions and appeared reluctant to reinstate any statewide protocols.

Responding to questions from reporters, Baker touted the state’s low hospitalization rates and high level of fully vaccinated people and said he will review the CDC guidance and consult experts before deciding whether to reimpose a mask mandate.

Baker did acknowledge he is considering new mask rules for schools, after the CDC this week recommended all students, teachers, staff, and visitors in K-12 schools should wear masks, regardless of vaccination status. Rhode Island officials Wednesday said they too will urge anyone attending or working in a school wear masks when the new term begins.

Dr. Philip J. Landrigan, director of the Global Public Health Program at Boston College and a practicing pediatrician, said the American Academy of Pediatrics also recommends masking requirements in schools.

“I would encourage the governor and the state Department of Education to follow the American Academy of Pediatrics’ mandate,” Landrigan said. “There’s no downside to doing what the American Academy of Pediatrics says. Their only raison d’être is to protect children’s health.”

Baker on Wednesday highlighted the state’s progress in getting people vaccinated — 4,339,778 fully vaccinated residents — and in lowering hospitalizations, in contrast to sections of the country where many are unvaccinated, the virus is running rampant, and some hospitals are filling.

“Remember, the federal government makes decisions and issues guidance for the country. . . . Massachusetts is in a very different place than the rest of the country,” he said. “We have the second-lowest hospitalization rate for COVID in the United States. We’ve had the second-lowest hospitalization rate for weeks. We have the second highest vaccination rate.”

In both cases, Baker said, only neighboring Vermont is ahead of Massachusetts.

“Those things factor into how we make these decisions, and they should. Because the vaccines work,” he said.

Medical specialists agreed that Massachusetts is better off than much of the country but stressed that the situation could change quickly.

“We may not want to do a statewide mask mandate yet, but we have to keep our ears to the ground and eyes on the horizon,” said Dr. Nahid Bhadelia, director of the Boston University Center for Emerging Infectious Diseases Policy and Research. “If cases go up, it might affect our ability to safely send kids back to school in the fall.”

Bhadelia said one of her biggest concerns is the reopening of large, indoor venues, and she hopes the state will consider reinstituting capacity restrictions in such spaces. Massachusetts dropped capacity limits along with other pandemic restrictions when the pandemic state of emergency ended May 29.

Landrigan said Baker is “very wise to say he’s evaluating things on a continuing basis, and he’s already shown that he’s willing to adjust his policies to changing circumstances.”

“The circumstance we’re in now, it’s sort of a mixed picture,” he said. “It’s clear that we have a very high vaccination rate in Massachusetts, and that’s good. . . . But at the same time, we’re seeing cases go up, we had that cluster in cases in Provincetown.”

The CDC advised that even vaccinated people should wear masks in indoor public spaces in parts of the country with at least 50 new cases per 100,000 people in the last week. That currently includes 60 percent of US counties, officials said.

Five Massachusetts counties are considered to have “substantial and high transmission” under the CDC’s guidelines: Suffolk (Boston, Chelsea, Revere, and Winthrop), Bristol (areas around Fall River, New Bedford, Taunton, and Attleboro), Barnstable (Cape Cod communities such as Provincetown, Falmouth, Sandwich, Dennis), Nantucket, and Dukes (mostly Martha’s Vineyard).

At the tip of Cape Cod, the COVID-19 cluster in Provincetown that first emerged earlier this month has ballooned to 833 cases, Town Manager Alex Morse said Wednesday, up 68 cases since Tuesday.

Morse said 501 of those infected live in Massachusetts and 210 are Provincetown residents. Seven have been hospitalized. The town adopted a new indoor mask mandate during an emergency meeting Sunday.

Bhadelia cautioned that one of the challenges ahead for the state will be to “find those pockets of areas within the state that are not as fully vaccinated as elsewhere, and to ensure that they don’t become the areas where the next cluster of cases occur.”

In Hardwick, a central Mass. town of about 3,300 people, just 35 percent residents were fully vaccinated as of July 22, according to the state.

“I have no idea how or why” the rate is so low, said town health agent Marcelino “Tex” Sarabia, who added that he didn’t necessarily agree with the state tally.

Correspondent Jasper Goodman contributed to this report. Material from Globe wire services was also used.

CLARIFICATION: An earlier version of this story imprecisely characterized Governor Charlie Baker’s comments regarding new CDC guidance.

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox. Sahar Fatima can be reached at sahar.fatima@globe.com Follow her on Twitter @sahar_fatima. Travis Andersen can be reached at travis.andersen@globe.com. Follow him on Twitter @TAGlobe.

Related Posts