“I applaud the move to get elementary schools back in person regardless of community transmission,” she said. “And I also understand that there is some hesitancy about applying that to middle and high school students, although I’m not sure that it is fully in keeping with the evidence that we’ve seen.”
Even with the new guidance, many issues relating to how schools will handle their reopenings remain contentious and unresolved.
Although the C.D.C. is continuing to recommend six feet of distance when children are eating, the fact that students need to remove their masks at lunch time has raised concerns for educators and their unions. Seattle, for example, is planning to reopen elementary schools in the coming weeks on a half-day schedule that would avoid meal times, giving students less than three hours per day of in-person schooling, only four days per week.
Meanwhile, some districts have kept schools closed one day a week for what is sometimes described as a day of “deep cleaning,” a practice that experts have said has no benefit. In Anne Arundel County, the cleaning day is why the district is aiming to bring students back four days a week this spring, rather than five.
“As we’re all learning as we go along, there’s the science and the data about safety, and then there’s the feelings about safety, and they’re not always completely in line,” Ms. Ellis, the board president, said.
C.D.C. officials relied on the findings of several new studies about viral transmission in schools to rewrite their guidelines. There was the study written by Dr. Branch-Elliman, Dr. Perkins and colleagues, which looked at school districts in Massachusetts and found no significant difference in the number of infections in school districts that used three feet of distancing, when compared with those that required six feet.
In addition, three new studies published on Friday looked at schools in Florida, St. Louis and Springfield, Mo., and Salt Lake County, Utah. The findings varied, but each paper emphasized the critical role that universal mask-wearing plays in curbing school-associated infections.
The Utah study looked at 20 elementary schools and found a low rate of viral transmission associated with schools between Dec. 3 and Jan. 31, despite high infection rates in the community. Most students wore masks, but limited classroom space made it impossible to keep them six feet apart, the study said; they were spaced closer to three feet apart.
Eliza Shapiro, Emily Anthes and Sheryl Gay Stolberg contributed reporting.