Rising COVID-19 cases have spurred action on face coverings

Pedestrians wore masks Thursday in Cambridge, where officials urged residents and visitors to wear masks in indoor public spaces.Matthew J. Lee/Globe staff

In one of the first signs the resurgence of COVID infections is causing concern among officials, Boston Acting Mayor Kim Janey on Thursday said all public school students in the city will be required to wear face masks when they return to classes in September.

Already this week, officials in Cambridge, Provincetown, and Nantucket urged residents and visitors to wear masks in indoor public spaces as new outbreaks have been reported; Cambridge, for example, said that 42 percent of the 83 confirmed and probable infections in July so far are “breakthrough” cases involving people who are fully vaccinated.

The case numbers and official responses in Massachusetts are still modest compared to other parts of the country where infections are rising sharply. The trend is largely driven by a worrisome combination of the emergence of the fast-spreading Delta variant and low vaccination rates, mostly in Southern and some Midwestern states.

On Thursday, Governor Charlie Baker, said he has no plans to reimpose statewide restrictions, but left the door open for local officials to set limits in their communities.

“We have a set of statewide standards, and they’re based on what we see on a statewide basis,” the governor said at an event on Cape Cod. “And if communities believe they need to pursue strategies that are more effective and appropriate to them, then they should do so.”

Janey revealed the safety precaution during a City Hall news conference, saying students in summer school and other city programs are currently wearing masks and noting that many children are not yet eligible for the vaccine.

“This fall they will be wearing masks still,” she said.

Janey’s comments came days after the American Academy of Pediatrics called for everyone older than age 2 to wear masks in school this fall, even if they have been vaccinated against COVID-19. The academy noted that federal regulators have not yet authorized COVID vaccines for children under age 12, leaving millions of youngsters vulnerable to infection.

Boston officials cautioned that while the number of infections is increasing, they have not reached a level to cause major concerns.

Baker rescinded the vast majority of COVID-19 restrictions in May and June, after millions of Massachusetts residents were vaccinated and the Centers for Disease Control and Prevention dramatically eased mask guidance for fully vaccinated people.

But in recent weeks, there has been a dramatic nationwide spike in new cases, driven in large part by the highly contagious Delta variant. In the past two weeks, there has been a 171 percent jump in infections in the United States, compared to a 27 percent increase globally, The New York Times reported.

The CDC has not changed its guidance that vaccinated people do not need to wear masks, but some communities across the nation have already begun restoring restrictions.

Los Angeles County imposed a requirement that residents mask in public again that went into effect last weekend. On Thursday, Atlanta Public Schools announced a “universal mask wearing” policy in all of the system’s school buildings when fall classes begin.

Dr. Rochelle Walensky, director of the CDC, warned Thursday that the Delta variant is the predominant strain in every region of the country and continues “spreading with incredible efficiency,”

She said the mutation is more aggressive and much more transmissible, calling it “one of the most infectious respiratory viruses we know of.”

“We are yet at another pivotal moment in this pandemic,” she warned. “We need to come together as one nation.”

In Massachusetts, despite a worrying outbreak in Provincetown that has infected more than 250 people, including many who were vaccinated, Baker sought to allay concerns Thursday.

The governor said the state is in a good position relative to the rest of the country and he remains encouraged by the thousands of vaccines being administered in Massachusetts every day.

Baker boasted that Massachusetts has one of the nation’s highest vaccination rates and said an uptick in cases is not as concerning as it would have been earlier this year.

While the COVID-19 vaccines used in the United States are highly effective, it is still possible for fully vaccinated people to contract the virus. However, so-called breakthrough cases are overwhelmingly less likely to lead to hospitalization or death.

“The difference between the impact of COVID on those that are vaccinated and those who aren’t is stark and profound,” Baker said.

On Wednesday, Nantucket’s Health and Human Services department issued an advisory asking residents and visitors to wear face masks indoors in public locations when they cannot be physically distanced from others, in light of the “increased virulence of the Delta variant, and its high ability to infect even those vaccinated in some cases.”

Provincetown officials also began asking vacationers and residents to wear masks after the outbreak there, which on Wednesday grew to 256 confirmed cases, including 190 Massachusetts residents. State data showed 64 new cases reported in Provincetown in the past two weeks and a test positivity rate of 12.34 percent.

Even as cases continue to rise after a low earlier this summer, Massachusetts and its highly vaccinated population are in better shape than much of the nation.

The average proportion of tests returning positive results here, about 1 percent, is a fraction of that in less vaccinated states, such as Missouri, where it tops 17 percent, and Louisiana, where it has crested 18 percent, according to the Mayo Clinic.

In Boston, Janey’s announcement that students must wear masks was met with the backing of the Boston Teachers Union, which has more than 10,000 members.

“With the uncertainty surrounding the delta variant, low vaccine rates for students 12-17 and no options for children under 12, we agree with Mayor Janey’s choice to play it as safe as possible,” said Jessica Tang, the union’s president, in a statement. “Once vaccines are available and approved for young children, it will certainly make sense to reevaluate, but right now we agree with the Mayor that these steps are necessary to protect the health and safety of our students.”

Christina Prignano of the Globe staff and correspondent Nick Stoico contributed to this report. Material from Globe wires services was also used.