RALEIGH, N.C. (WNCN) — A team of researchers found “extremely limited” secondary spread of COVID-19 in its study of the K-12 schools across North Carolina that followed mitigation measures including masking and distancing.

The study by the ABC Science Collaborative, a joint effort from researchers at Duke University and the University of North Carolina, found just 32 cases of secondary transmission in schools among roughly 90,000 students and staff in 11 districts across the state with in-person instruction over nine weeks last fall.


“I would like to think that parents can look at the study and draw a lot of confidence from it,” said Dr. Bob Grimesey, superintendent of Moore County Schools, one of the districts taking part in the study.

The researchers found there were 773 lab-confirmed COVID-19 infections acquired via the community, and wrote that they expected up to 900 infections in schools if secondary transmission were as common there as in the community.

Instead, through contact tracing, they found about 30 times fewer school-related cases than anticipated.

The key, one of the lead researchers told CBS 17 News, is adherence to and enforcement of the mitigation strategies of masking, distancing and hand-washing.

“Transmission is low in the setting — having the ‘Three Ws,’ following the mitigation strategies, that’s what should be taken away,” said Dr. Kanecia Zimmerman of the Duke Clinical Research Institute, one of the lead researchers of the study.

“Whether the absolute numbers are 32 or 320, they still are less than what we would have expected out in the community,” she added. “The message is consistent with what’s been seen in the (United Kingdom), what’s been seen in other places in the United States. Even when there was a lot of very robust contact tracing, very robust testing, the message has been the same.”

Six of the 32 cases were in pre-K with 11 in elementary schools, six in middle schools and five in high schools. Another four were in schools with students in all 13 grades.

The study does come with limitations. Participation in ABC is voluntary and not every district took part — 56 of the state’s 115 districts joined the collaborative in August — and those involved already may have been more likely to enforce adherence to those preventative measures. And because testing is not required to return to schools in the state, the researchers couldn’t make sure everyone was tested.

“But we do know that in the setting of schools, contact tracing’s going to be pretty good,” Zimmerman said. “We are motivated, and we know who’s in the school building, and testing’s going to be at least as good as it is in the community. 

“The remarkable thing is that transmission was really low,” she added. “And even if you bar the numbers — like, times 10, let’s assume we missed a lot of cases. It’s still lower than what we were seeing in the setting of the community.”

The study will be published by the American Academy of Pediatrics.

CBS 17’s Joedy McCreary has been tracking COVID-19 figures since March 2020, compiling data from federal, state, and local sources to deliver a clear snapshot of what the coronavirus situation looks like now and what it could look like in the future.