The Centers for Disease Control and Prevention on Friday said schools often only need to maintain three feet of space between masked students to reopen classrooms, clearing the way for more students to resume in-person learning.

Universal masking in the classroom would be needed to safely use three feet of distance, rather than the previously recommended six feet between people in schools, the CDC said.

All elementary schools can adhere to the three-feet guidance without major risks, as can middle and high schools in communities where transmission is low, moderate or substantial — meaning in places with up to 99 cases per 100,000 people in the past seven days — but not where it’s “high,” or more than 100 cases per 100,000 people within seven days.

The CDC recommends that middle and high schools in high-transmission areas continue to keep students six feet apart if cohorting — or keeping students within distinct groups throughout the day — is not possible. The agency said this reflects how the virus that causes COVID-19 seems to spread more easily among older students and affect them more.

Adults in schools should keep six feet of distance between themselves and students, the CDC said.

“The evidence shows the risk of COVID transmission among younger children is much lower than it is among teenagers and adults. And in particular, our school studies have shown that when children, young children are masked, the distance of three feet is safe,” CDC Director Rochelle Walensky said in a press briefing. “For adults, we don’t have that evidence, and for older children, and so we’re continuing with the six-foot guidance.”

The agency also suggested everyone keep six feet of distance when masks can’t be worn, such as while eating; in common areas; and during activities such as band, choir practice or sports.

Those riskier activities like eating, choir practice, band practice and schools sports should be conducted outside whenever possible, or in large, well-ventilated areas, Walensky told reporters.

“CDC is committed to leading with science and updating our guidance as new evidence emerges,” Walensky said in a statement. “Safe in-person instruction gives our kids access to critical social and mental health services that prepare them for the future, in addition to the education they need to succeed.”

Teachers’ concerns

President Joe Biden said safely reopening schools was a top priority for his administration, but Republicans have criticized him for siding with teachers unions and argue he should move faster to return students to the classroom.

The American Federation of Teachers, a teachers union, expressed concerns Friday about the updated Biden administration guidance.

“Kids need to be in school, and the AFT has advocated consistently for safely reopening in-person learning since last April, but we are concerned this change has been driven by a lack of physical space rather than the hard science on aerosol exposure and transmission,” said President Randi Weingarten in a statement.

A majority of students already attend in-person at least in some capacity, with some school districts using practices that either flout mitigation recommendations or barely fall within the guidance’s advice. Many schools have outdated ventilation systems, according to the Government Accountability Office.

Walensky said she had been in contact with teachers unions about the changes.

“I’ve spoken to the teachers unions. They know we need to follow the science and to make our guidance based on that science and they have been very respectful of that,” she said.

Research, including a trio of new studies from Missouri, Utah and Florida the CDC released Friday, suggests that students can safely be in the classroom with three feet of distance between masked students. Experts agree children’s mental and physical health benefits from being in the classroom instead of learning at home.

But one of those studies, conducted in Florida where most K-12 schools opened for in-person learning last fall, found that higher rates of students contracting COVID-19 were observed in smaller districts, districts that did not require mandatory masking and those with a lower proportion of students participating in remote learning.

“These findings highlight the importance of implementing both community-level and school-based strategies to reduce the spread of COVID-19 and suggest that school reopening can be achieved without resulting in widespread illness among students in K–12 school settings,” the study says.

The change in guidance comes after Walensky told lawmakers this week that the previous distancing guidance had made it more difficult for schools to reopen. She hinted that revisions were coming.

“As soon as our guidance came out, it became very clear that six feet was among the things that was keeping schools closed,” she said Wednesday. “And, in that context, science evolves.”

The administration also announced this week it would direct $10 billion to schools for COVID-19 testing.

Warning about variants

Meanwhile, White House chief medical adviser Anthony Fauci updated warnings about the circulation of a more dangerous variant.

Fauci told reporters the B.1.1.7 variant that originated in the United Kingdom and is circulating widely throughout the United States is 50 percent more transmissible than the original strain and could be more severe.

The vaccines appear to be effective against the variant, said Fauci, who urged people to continue mask-wearing and social distancing.

“We’re at a position right now where we’re at a plateauing of 50,000 cases per day. The concern is that throughout the country there are a number of [places] that are pulling back on some of the mitigation measures,” Fauci said. “It is really quite risky to declare victory before you have the level of infection in the community to a much, much lower level than 50,000 cases per day. So it is unfortunate but unsurprising to me that you are seeing increases in the number of cases per day in certain areas, cities, states or regions, even though vaccines are being distributed at a pretty good clip of 2 to 3 million per day.”

The positive impact of vaccination “could be overcome if certain areas pull back prematurely on the public health and mitigation measures that we all talk about,” Fauci said.