Vaccinated students should be allowed to go to school without masks on, according to updated COVID-19 guidance state education and health leaders released Friday.

The guidance comes three days after the U.S. Centers for Disease Control and Prevention urged everyone to wear masks indoors in places with "substantial" or high transmission, regardless of vaccination status. The CDC also recommended that all students and school staff wear masks.

Massachusetts' guidance leaves it up to individual school districts to decide whether to have mask requirements in the new school year, an issue which has been causing heated debate in some cities and towns. The state has already removed remote learning as an option for most districts.

"One thing's clear: all schools and all districts must be open every day to every student no matter what," Baker said at a press conference Friday. "The documented negative impact on children that resulted from the uneven, unpredictable and profoundly difficult year that students had last year can not and must not happen again."

The memo by Massachusetts leaders did not make any requirements of schools, but did "strongly recommend" unvaccinated staff and students wear masks when indoors (particularly children under age 12 who are not yet eligible for vaccination). The memo cited high vaccination rates in the state overall and research showing children generally have a lower risk of serious illness from the coronavirus.

The recommendation that vaccinated students be able to shed their face coverings inside Massachusetts schools also came as the state issued updated guidance advising unvaccinated people, people who may be more vulnerable to serious illness due to age or medical conditions and those that live with them to wear masks in indoor spaces outside their homes.

The state policy seems to depart from stricter national guidance, issued this month by both the Centers for Disease Control and the American Academy of Pediatrics, which calls for universal masking of at least unvaccinated people in schools. Baker enlisted the latter group during his push to reopen school buildings earlier this year.

Merrie Najimy — president of the Mass. Teachers Association, the state’s largest teacher’s union — said she learned of the “reckless” policy half an hour before it was formally published.

“We don’t feel that this is any kind of guidance at all,” Najimy said. She added that the union is committed to in-person learning, but helped along by “upgrades to building ventilation, regular surveillance testing” and the use of masks — at least until the latest, delta-driven outbreak shows signs of waning or the vaccine is available for children younger than 12.

Tracy O’Connell Novick, a member of the school committee in Worcester, said she feels “let down” by the latest state intervention.

“Think of the choices families have to make right now, in particular for families with children that have any kind of vulnerability” to the virus, Novick said. With masks optional but fully in-person learning mandatory, per state policy, “what kind of choices do they have?”

As he defended the policy Friday, Baker said that broad differences between districts — in their rates of transmission and of vaccination — were “part of the reason we believe that we should issue this as guidance, with recommendations,” rather than a stricter, statewide policy.

Several school committees are weighing whether to mandate masks in their districts. Boston Mayor Kim Janey said last week that all students and staff would be required to wear masks in schools this fall.

The policy does have more vociferous supporters in the medical community.

Shira Doron was one of three physicians to call for an end to mandatory masking in an op-ed published by U.S. News earlier this month. For her, the state policy “did a great job of threading a really difficult needle.”

“The [CDC] recommendations are for an entire country, some of which is on fire again — drowning in COVID, with overwhelmed hospitals,” Doron noted. She added that any such guidance needs to be adapted to localities, “using the prevalence of disease, and the proportion of the population that’s vaccinated, to make those decisions.”

In Doron’s view, Massachusetts’ high rates of vaccination, and children’s lower susceptibility to serious health risks from COVID, make dangerous outbreaks in school buildings relatively unlikely — even without everyone wearing a mask.

The CDC relied on new data in developing its mask guidance this week, obtained by The Washington Post, which showed the delta variant is more transmissible than other variants, even in vaccinated people. The research did also show that the vaccines were very effective at reducing the risk of serious illness and hospitalization. According to several reports, the CDC also weighed research of a recent outbreak of COVID-19 in Provincetown.

Under a federal order, students and staff are required to wear masks when on school buses.

State education and health leaders are planning to release updated protocols for responding to suspected or confirmed cases of COVID-19 in schools, moving away from quarantining students or staff. The memo said districts with COVID-19 testing will be able to use what the state calls a "test and stay" protocol — where close contacts who are asymptomatic or vaccinated would not have to quarantine, but could remain in school and be tested each day with a rapid antigen test.

Massachusetts health officials are now advising some people who are fully vaccinated against COVID-19 to wear masks when inside places that are not their homes.

The updated state guidance released Friday applies to people who are fully vaccinated and are "at risk for severe disease because of your age or an underlying medical condition." Vaccinated people who live with those who have a weakened immune system or are unvaccinated are also advised to mask up indoors.

That includes anyone who lives with children under 12, who are not yet authorized to get any of the COVID vaccines.

In a statement, state Department of Public Health officials said the advisory comes in light of updated guidance released by the U.S. Centers for Disease Control and Prevention on July 27.

The statement reads in part:

The updated CDC guidance continues to state that individuals who are fully vaccinated may, as a general matter, resume many of the activities that they engaged in prior to the pandemic without wearing a mask or staying 6 feet apart, except where otherwise required by federal, state, or local laws, rules or regulations.

In response to the recent spread of the Delta variant, however, the CDC’s updated guidance does recommend that even fully vaccinated persons wear masks or face coverings when indoors if other risk factors are present.

At a press conference Friday in Roxbury to promote vaccinations for children 12 and older, Gov. Charlie Baker discussed the state's new advice on coronavirus precautions for the vaccinated, stressing the effectiveness of vaccines in preventing hospitalizations and deaths in the state.

"This new guidance was developed to be as simple and as straightforward as possible, and we also tailored it to Massachusetts," Baker said. "... The vaccines work, and we're going to continue to do everything we can to make sure that everyone who wants one can get one and can get one easily."

Repeating the new guidance, Baker said that those who have or live with people with underlying health conditions should "take greater precautions" to protect themselves and their loved ones from the virus.

The new state guidance stops short of requiring vaccinated people to wear masks in areas with significant coronavirus transmission as recommended by the CDC. There are several Massachusetts counties that meet the CDC definition of "substantial" or high transmission.

Also Friday, the Department of Elementary and Secondary Education said it and DPH "strongly recommend that all students in kindergarten through grade 6 wear masks when indoors, except students who cannot do so due to medical conditions or behavioral needs" and that "schools allow vaccinated students to remain unmasked."

At earlier points in the coronavirus pandemic, Massachusetts has mandated that everyone wear masks or face coverings inside nearly all businesses and other public places. The state ended its mandatory mask policy in late May.

After that change, state officials and many businesses urged residents who are unvaccinated to continue wearing masks in public.

Currently, the state still requires people entering health care facilities and those using public transportation and ride-hailing services to wear face coverings. That requirement will remain in effect.

In updating their guidance, state officials continued to urge residents to get vaccinated.

"COVID-19 vaccines are highly effective and every individual who is eligible and either works, studies or resides in Massachusetts is advised to get vaccinated," the advisory stated.

Gov. Charlie Baker said Wednesday he is not considering reimposing travel restrictions on residents or visitors amid the latest rise in COVID-19 infections and hospitalizations and said he will "have more to say shortly" about federal masking guidance issued on Tuesday once his administration has a chance to review it more thoroughly.

Though the governor deflected most questions about the U.S. Centers for Disease Control's recommendation that everyone — including those who are fully vaccinated against COVID-19 — go back to wearing a mask when in indoor public spaces in areas where the Delta variant is fueling "high" or "substantial" viral transmission, he argued that the COVID-19 situation in Massachusetts is not as bad as it is elsewhere.

For a few months, fully vaccinated individuals were able to let their faces be uncovered in government-sanctioned masklessness.

That era might soon be coming to an end.

The Centers for Disease Control and Prevention released new mask guidance Tuesday, recommending fully vaccinated people resume wearing masks indoors in regions where COVID-transmission is high.

CDC Director Dr. Rochelle Walensky said on a call with press that the decision came after reviewing data on the delta variant and breakthrough cases among vaccinated people.

WBUR health reporter Angus Chen was on that call, and joined WBUR's Morning Edition to discuss.

Fully vaccinated Massachusetts residents have until just before midnight to enter the first drawing of the state's $1 million vaccine lottery.

The Thursday deadline is for the first of five weekly drawings in the state's vaccine lottery, which was created to entice more residents into getting inoculated against COVID-19. If you miss out on the first drawing, you still can throw your name in the hat for the other four.

State Treasurer Deb Goldberg, who oversees the state lottery, said just under half of those eligible have signed up for the contest so far. For adults, there are a total of five $1 million prizes at stake. And for those between the ages of 12 and 17, there are five $300,000 scholarship prizes up for grabs. Each drawing will select one winning adult and child, respectively.

"You're going to see a really excited million-dollar winner, and you're going to see a really excited teenager who will know that they're not going to go into debt from getting their education," Goldberg said.

Residents have until 11:59 p.m. Thursday to sign up for the first drawing, which will be held on July 26 and announced on July 29. Once registered, people will automatically be eligible for the subsequent drawings.

The Massachusetts Department of Public Health is monitoring a coronavirus outbreak at a nursing home in West Yarmouth.

As of Monday, 24 residents and nine staff members of the Maplewood at Mayflower Place home have tested positive for the virus, a DPH spokesperson confirmed.

The majority of the 33 people are vaccinated, and are either asymptomatic or have mild symptoms. DPH says residents who tested positive have been offered monoclonal antibody treatment.

The first positive case was confirmed on July 10.

Nursing homes in Massachusetts were hard hit early in the pandemic. Thousands died in facilities across the state. Nursing home populations were among the priority groups during the vaccination roll out earlier this year. As of last month, DPH says, 88% of nursing home residents are fully vaccinated and 73% of staff are fully vaccinated.

Public health officials have tracked 4,450 "breakthrough" cases of COVID-19 among Massachusetts residents fully vaccinated against the disease, representing about one-tenth of 1% of the roughly 4.2 million people immunized.

About 92% of the infections in vaccinated residents did not require hospitalizations, while 303 people, or 6.8%, were hospitalized, according to Department of Public Health data through July 10.

The Boston Herald first reported the breakthrough data on Tuesday based on a public records request.

Seventy-nine vaccinated residents in Massachusetts died from COVID-19, either without being hospitalized or following a hospital stay, DPH said. That death toll reflects 1.78% of the 4,450 confirmed breakthrough cases and 0.0019% of the 4,195,844 people fully vaccinated as of July 10.

Health experts have said occasional infections after vaccinations are expected but that the immunizations greatly reduce the chances that contracting COVID-19 will lead to serious complications or death.

Since the pandemic began, DPH has confirmed 665,088 COVID-19 infections and 17,647 deaths — the bulk of which occurred before most residents had access to vaccines — for a fatality rate of nearly 2.7%.

The pace of new vaccinations has slowed considerably in recent weeks leading up to and after the June 15 end of the state of emergency. In the seven-day period ending May 30, the state averaged 41,918 vaccine doses administered per day, but that rate dropped to 10,880 for the seven-day period ending July 2.

Gov. Charlie Baker's administration has ramped up its focus on more targeted vaccine initiatives, supporting door-knocking campaigns, local outreach and incentive programs such as a state-run "VaxMillions" lottery open only to those who are fully dosed.