With universal masking, just 3 feet of distancing is safe for students in many classrooms, the Centers for Disease Control and Prevention announced in updated guidance released on Friday.

According to the new recommendations, elementary schools with universal masking policies are advised to maintain at least 3 feet of distancing between students in classrooms, regardless of the current level of community transmission of SARS-CoV-2.

Middle and high schools with universal masking are also advised to maintain at least 3 feet of distancing between students in classrooms if community transmission is currently low, moderate, or substantial. If the community transmission is high and student cohorting/podding is not possible, then distancing of at least 6 feet should be maintained in middle and high school classrooms.

The guidance updates apply only to students in school classrooms when universal masking is in place.

The agency still recommends 6 feet of distancing between adults in schools, between adults and students in schools, and in any common areas of schools (not classrooms), such as lobbies and auditoriums. The agency also continues to recommend 6-feet of distancing in pretty much every other community setting, particularly when masks can’t be worn, such as while eating and when there’s increased exhalation, such as from shouting or singing.

Distancing debate

The tweaked guidance comes amid renewed pressure over the agency’s previous stance, that schools should maintain six feet of distancing at all times and in all places. The guidance drew fire and has been heavily scrutinized because the distance is extremely prohibitive for schools. Classrooms are simply not large enough to accommodate that much spacing. Many parents, school officials, politicians and even public health experts have questioned whether 6 feet is needed, particularly as some health agencies—including the World Health Organization—have said that at least 3 feet of distancing is sufficient.

The debate was rekindled last week when a new study claimed that Massachusetts’ public schools with 3-feet distancing policies had the same rates of SARS-CoV-2 transmission as schools with 6-feet distancing policies. The study was quickly picked up by 3-feet spacing advocates. But it had some significant limitations and noisy statistics. In fact, the confidence intervals were so large in the analysis that 6 feet of distancing could have decreased case rates as much as 47 percent compared with 3 feet or could have also increased case rates by as much as 18 percent. Both possibilities were plausible, according to the data.

Still, the study put pressure on the CDC to revisit its guidance. Earlier this week, CDC Director Rochelle Walensky confirmed that the agency was looking through the data and had additional studies in the works to address the spacing issue.

In a Senate committee hearing Thursday, Sen. Susan Collins, R-Maine, pressed Walensky further to cut distancing from 6 feet to 3 feet, telling her bluntly, “You need to do it now.”

New data

With the announcement of the distancing cut for classrooms, the CDC released three studies looking at transmission of SARS-CoV-2 in schools, though none of them compare rates in schools that used 3-feet distancing versus those with 6-feet distancing.

A two-week study of 22 K-12 schools in the city of Springfield, Missouri, and in St. Louis County, Missouri concluded that, even with high levels of SARS-CoV-2 transmission in the community, school transmission was low when masking and distancing was in place. In the brief study, 37 students, teachers, and staff tested positive for SARS-CoV-2. They had a total of 157 school-based contacts, of which 102 were tested for the virus. Only two tested positive, suggesting low in-school transmission. In the 22 schools, 100 percent had universal masking, 100 percent spaced desks ≥3 ft apart, 27 percent spaced desks ≥6 ft apart, and 98 percent placed physical barriers between teachers and students.

Another of the studies looked at elementary schools in Utah. It found that even with high community transmission and an inability to maintain 6 feet of distancing in the schools, SARS-CoV-2 transmission was low among the elementary school students and staff. The third study, conducted in Florida, likewise found that transmission was low in schools. Researchers estimated that about 40 percent of COVID-19 cases in school-aged children were linked to schools.

All three studies have notable limitations, including not screening for possible asymptomatic cases in students not identified as contacts, and many contacts declining testing. Still, the data was enough to sway the health agency.

“CDC is committed to leading with science and updating our guidance as new evidence emerges,” Walensky said in a press 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. These updated recommendations provide the evidence-based roadmap to help schools reopen safely, and remain open, for in-person instruction.”