WITH TUESDAY’S ANNOUNCEMENT by state officials that they want to see all elementary grade students back in classrooms five days a week by April, now comes the hard part of the details of how to do it. 

Looming large in the challenge of getting students back into classrooms is a term that’s become part of the daily lexicon of pandemic policy debates: social distancing. Call it the elephant in the classroom. 

Most public health recommendations have urged people to maintain at least six feet of separation from those not in their household. The federal Centers for Disease Control says six feet should also apply in school settings. But the state Department of Elementary and Secondary Education, in guidelines for the school year released last June, said three feet is adequate. 

The state guidelines encourage districts to “aim for six feet of distance between individuals where feasible,” but say maintaining a distance of three feet, in combination with other mitigation efforts, “is informed by evidence and balances the lower risk of COVID-19 transmission and the overarching benefits of in-person school.” The state guidelines note that this approach aligns with recommendations of the World Health Organization, which says one meter (three feet, three inches) of social distancing is adequate to reduce risk of transmitting coronavirus. 

State officials point to evidence of much lower transmission rates among younger children and enforcement of masking and other safety measures in schools that aren’t assumed to be in place in the six-foot recommendations for people in other settings. 

The CDC restated its six feet standard as part of a set of new school reopening recommendations issued earlier this month. 

Reacting to the new CDC guidelines, 60 Boston area infectious disease physicians and public health experts signed a letter to state education commissioner Jeff Riley raising doubts about the federal standard and voicing support for the state’s three-feet recommendation. 

The health experts said they have “concerns with the Return to School guidelines recently released by the CDC” and wanted to “reinforce our conviction that the guidelines set out by the Department of Elementary and Secondary Education (DESE) in June 2020 are more appropriate to guide Massachusetts, particularly with regard to distancing between students and that opening schools to in-person learning should reflect within school transmission rather than strictly community COVID prevalence rates.”

They said the CDC guidelines fail to take stock of successful efforts to implement mitigation measures in schools that dramatically reduce transmission risk, even in communities with high overall community COVID-19 rates. 

The debate between three and six feet has big implications for school reopenings, as many schools would not be able to have all students return to their classroom with six feet between them. Indeed, that’s been part of the rationale for hybrid models that have divided students into two cohorts, with each group in school two days a week. It’s easier to meet the six-feet standard with half as many students in classrooms. 

In Fairhaven, school superintendent Robert Baldwin said the district has been able to have just first- and second-grade students back in-person all year, but that’s been achieved by dividing classes up and making use of other spaces in schools so that there are no more than 12 students in any classroom. That would probably be tough to do if all elementary grade students were brought back to the district’s schools. 

“We worked off of six feet,” said Baldwin. As for the idea of reopening schools with three feet of distance, he said, “I’m going to be honest. I’m not a scientist. You give me scientific evidence on what’s best for kids, I’m going to follow that.”

Balancing what’s best for kids, say education officials, takes account of both the virus risks of in-person learning and the harm that nearly all agree is coming from young people being marooned at home. 

There is no sudden protection from coronavirus that kicks in when people are six feet apart. Last week, the Brookline schools released a summary of what it calls the “scientific consensus” that supports a “reduction of 6-foot distancing parameters.” 

In terms of the impact of social distancing, it says the “risk reduction is a gradient, not a binary, effect.” That means there may be less risk at six feet than at three, but it may not be that large. Indeed, the summary says “the absolute reduction in transmission risk going from 3-foot to 6-foot distancing is very small to practically non-existent in a low-risk setting (e.g., as a result of universal mask wearing, enhanced ventilation, and other mitigation measures in our schools).” 

Sometimes where you stand on an issue depends on where you sit. 

The new director of the Centers for Disease Control and Prevention under President Biden, Dr. Rochelle Walensky, came to the agency from Massachusetts General Hospital, where she was an infectious disease physician. Interviewed earlier this month by CNN’s Jake Tapper, Walensky defended the new CDC school opening guidelines. But Tapper showed a private email CNN obtained that Walensky sent last July to Newton Mayor Ruthanne Fuller saying she believed three feet of distance between students was “quite safe,” especially if they are masked. 

Asked what’s changed, Walensky said virus rates were much lower in the summer when she wrote that, and that we have new evidence and new concerns now, such as the coronavirus variants that have emerged. “We have to be humble as to what we’re learning and be willing to be flexible as we learn more,” she said.