Health officials say evidence continues to mount that it’s generally safe to have in-person schooling, if U.S. schools require mask wearing and other precautions.

The latest study looks at schools in rural Wisconsin and found cases linked to in-school transmission were very low even while infections were common in the same communities.

Margaret Honein of the Centers for Disease Control and Prevention says,

“Data has really accumulated over the last few months that with good prevention efforts … we can keep transmission in schools quite low.”

The Wisconsin study was published online Tuesday by a CDC journal, Morbidity and Mortality Weekly Report. It focused on 17 schools in Wood County in central Wisconsin and found cases were diagnosed at rate 37% lower than reported in the county overall.

In the Journal of the American Medical Association, Honein and other CDC scientists say it’s re-assuring that the kind of spread seen in nursing homes and other places hasn’t been noted in schools with prevention measures.

However, they say some extracurricular school-related activities, such as sports, have triggered coronavirus spread in some places.