Vaccinated teachers and students no longer need to wear masks inside school buildings, the U.S. Centers for Disease Control and Prevention said Friday, further relaxing its COVID-19 guidelines for schools.

The Maine Center for Disease Control and Prevention took similar action on July 1, dropping its requirement that everyone wear face coverings in elementary- through high-school buildings and in other child care settings. It was the last state-level mask requirement to be lifted in Maine; federal law still requires face coverings to be worn in all public transportation and related indoor areas.

The updated federal guidance for schools comes amid a national vaccination campaign in which children as young as 12 are eligible to get shots, as well as a general decline in COVID-19 hospitalizations and deaths, The Associated Press reported.

“We’re at a new point in the pandemic that we’re all really excited about,” so it’s time to update the guidance, said Erin Sauber-Schatz, who leads the federal CDC task force that prepares recommendations designed to keep Americans safe from COVID-19.

The Maine CDC continues to recommend, though not require, that unvaccinated people wear face coverings indoors, including those under age 12 who are not yet eligible for a COVID vaccine, said spokesman Robert Long.

“We are pleased that the (federal) guidance aligns with the recommendations that we have already provided to school systems,” Long said Friday. “We are also pleased that U.S. CDC agrees with Maine’s assessment about the value of pooled testing, which we have made available to Maine school districts at no cost since May.”

Long said the Maine CDC and Department of Education will closely review the new federal guidelines for schools, which also say:

• Masks aren’t needed at recess or in most other outdoor school situations, but unvaccinated people are advised to wear masks at crowded outdoor events, such as in the stands at football games.

• Ventilation and hand-washing continue to be important. Students and staff also should stay home when they are sick.

• Teaching students in smaller groups, or cohorts, continues to be a good way to help reduce virus spread, but to avoid stigmatizing students, schools shouldn’t separate vaccinated and unvaccinated kids.

• Testing remains an important way to prevent outbreaks, but people who are fully vaccinated don’t need to participate.

Long said the Maine Department of Health and Human Services will continue to encourage schools to participate in its free pooled testing program, which reduces the spread of the virus in schools and eliminates the need for quarantining for participating students and staff who are asymptomatic.

In addition, individual school districts and child care settings may continue to require face coverings, as some Maine businesses have done.

“The Mills administration continues to expect all schools to offer full-time, in-person education this fall,” Long said.

The U.S. CDC is not advising schools to require shots for teachers and vaccine-eligible kids, the AP reported. And it’s not offering guidance on how teachers can know which students are vaccinated or how parents will know which teachers are immunized.

That’s probably going to make for some challenging school environments, said Elizabeth Stuart, a Johns Hopkins University public health professor who has children in elementary and middle schools.

“It would be a very weird dynamic, socially, to have some kids wearing masks and some not,” Stuart said. “And tracking that? Teachers shouldn’t need to be keeping track of which kids should have masks on.”

Another potential headache: Schools should continue to space kids – and their desks – 3 feet apart in classrooms, the U.S. CDC says. But the agency emphasized that spacing should not be an obstacle to getting kids back in schools. And it said distancing is not required among fully vaccinated students or staff.

All of this may prove hard to implement, and that’s why the U.S. CDC is advising schools to make decisions that make the most sense at the local level, Sauber-Schatz said.

The biggest questions will be at middle schools, where some students are eligible for shots and others aren’t. If sorting vaccinated and unvaccinated students proves too burdensome, administrators might choose to just keep a masking policy in place for everyone.

In some of the nation’s largest school districts, widespread mask-wearing is expected to continue this fall. In Detroit’s public schools, everyone will be required to wear a mask unless everyone in the classroom has been vaccinated. Philadelphia will require all public school students and staff to wear masks inside buildings, even if they have been vaccinated. But masks won’t be mandated in Houston schools.

What about requiring COVID-19 vaccination as a condition of school attendance? That’s commonly done across the country to prevent spread of measles and other diseases.

The U.S. CDC has repeatedly praised such requirements, but the agency on Friday didn’t recommend that measure because it is considered a state and local policy decision, agency officials said.

Early in the pandemic, health officials worried schools might become coronavirus cauldrons that spark community outbreaks. But studies have shown that schools often see less transmission than the surrounding community when certain prevention measures are followed.

The new guidance is the latest revision to advice the CDC began making to schools last year.

In March, the CDC stopped recommending that children and their desks be spaced 6 feet apart, shrinking the distance to 3 feet, and dropped its call for use of plastic shields.

In May, the agency said Americans in general don’t have to be as cautious about masks and distancing outdoors, and that fully vaccinated people don’t need masks in most situations. That change was incorporated into updated guidance for summer camps – and now, schools.

Becky Pringle, president of the National Education Association, called the new federal guidance “an important roadmap for reducing the risk of COVID-19 in schools.”

U.S. Secretary of Education Miguel Cardona pledged to work with schools to help them get kids back into classrooms.

“We know that in-person learning offers vital opportunities for all students to develop healthy, nurturing relationships with educators and peers, and that students receive essential supports in school for their social and emotional well-being, mental health, and academic success,” he said in a statement.