At the same time, many neighborhood parents, especially poor and non-white parents, are reluctant to send their children back to school, even if they have the option, for fear that their children will get sick and possibly bring the virus home.

Schools in New York City, Chicago, Boston and other cities have partially reopened or are starting to reopen. But the conflict between elected officials who support the reopening and teacher unions is likely to continue despite the new guidelines in places like Los Angeles, San Francisco and Portland, Oregon.

School district leaders have long been demanding clearer guidelines from the federal government on how to make decisions during the pandemic. The CDC’s advice is a relief to many experts who have been frustrated with the low priority given to schools in local reopening plans.

“It doesn’t mean you will open schools again,” said Helen Jenkins, an infectious disease expert at Boston University and advisor to the public school district in Cambridge, Massachusetts. They say, ‘They’re going to open schools again, and this is how it goes, which I really appreciate. “

The agency’s approach striked the right balance between the risks and benefits of in-person teaching, said Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health.

“We have done a tremendous amount of damage because we haven’t opened schools,” said Dr. Nuzzo. “This document is important to identify the risks related to this damage and to find a way forward.”

The CDC encouraged elementary schools to stay open regardless of virus levels in the surrounding community, citing evidence that toddlers are the least likely to be infected or to spread the virus. Middle schools and high schools should not switch to virtual learning until community transmission of the coronavirus reaches its highest levels, the agency said.