The spread of COVID-19 during in-person learning in rural Wisconsin where student mask wearing was high was significantly lower than in the surrounding community, with no infections acquired at school among staff members, according to a U.S. study published on Tuesday.
That COVID-19 incidence in the 17 elementary through high schools was 37% lower than in the community suggests schools could safely open with the right precautions in place, researchers concluded in the report published by U.S. Centers for Disease Control and Prevention (CDC), reports Reuters.
“Given the findings of our data set, with proper precautions such as distancing and wearing face coverings, it seems that adult school staff members are unlikely to contract COVID-19 in the classroom,” study author Amy Falk, from the Aspirus Hospitals and Clinics, said in an emailed response.
CDC scientists in a separate article published in JAMA also supported the reopening of schools provided social distancing and mask-wearing measures are implemented.
While there had been some evidence of in-school transmission, “the preponderance of available evidence from the fall school semester has been reassuring,” they said.
“As many schools have reopened for in-person instruction in some parts of the U.S. as well as internationally, school-related cases of COVID-19 have been reported, but there has been little evidence that schools have contributed meaningfully to increased community transmission,” the CDC said.
In the Wisconsin study, just seven of 191 cases (3.7%) identified among 5,530 students and staff members during the period of Aug. 31 to Nov. 29, 2020, were associated with in-school transmission, all in students, researchers reported.
“The absence of identified child-to-staff member transmission during the 13-week study period suggests in-school spread was uncommon,” the researchers said, despite up to a 40% positive COVID-19 test rate in the surrounding county.
Social distancing was required and mask-wearing was reported at more than 92%. Classes were taught in stable cohorts with both lunch and classes taking place indoors. Lunch took place mainly in the cafeteria, in assigned cohorted groups for ease of contact tracing. But no systematic COVID-19 screening was conducted in the schools or the community.
The researchers found widespread virus transmission in the surrounding community during the study period, with 7% to 40% of COVID-19 tests from Wood County showing positive results.
COVID-19 incidence among students and staff members in the study translated into 3,453 cases per 100,000 in schools versus 5,466 per 100,000 in the wider community.
The schools in the study included eight elementary schools (grades K–6) with 1,529 students attending in-person, and nine middle or high schools (grades 7–12) with 3,347 students attending in-person.
Limits to the study published in the CDC’s Morbidity and Mortality Weekly report, included that researchers did not check for asymptomatic transmission and that not all teachers reported mask wearing levels.