Schools operating in person have seen scant transmission of the coronavirus, particularly when masks and distancing are employed, but some indoor athletics have led to infections and should be curtailed if schools want to operate safely, researchers from the Centers for Disease Control and Prevention concluded in papers published Tuesday.

The CDC team reviewed data from studies in the United States and abroad and found the experience in schools different from nursing homes and high-density worksites where rapid spread has occurred.

“The preponderance of available evidence from the fall school semester has been reassuring,” wrote three CDC researchers in a viewpoint piece published online Tuesday in the Journal of the American Medical Association. “There has been little evidence that schools have contributed meaningfully to increased community transmission.”