CDC: In-school spread of COVID-19 37% lower than community transmission

The spread of COVID-19 was lower in K-12 schools offering in-person instruction than in the surrounding community, according to a study released Tuesday. 

The study, which involved 17 K-12 schools in five rural Wisconsin districts, found that COVID-19 incidence in schools with in-person instruction was 37% lower than that in the surrounding community despite widespread community transmission. COVID-19 incidence among students and staff members was 3,453 per 100,000 compared to a community transmission rate of 5,466 per 100,000.

Only 191 COVID-19 cases were reported among 5,530 students and staff members and only seven (3.7%) of these cases were linked to in-school transmission, researchers at the Centers for Disease Control and Prevention found. No infections among staff members were linked to in-school spread. 

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“The coronavirus disease 2019 (COVID-19) pandemic has disrupted in-person learning in the United States, with approximately one half of all students receiving online-only instruction since March 2020,” the CDC researchers wrote in the study. “Discontinuation of in-person schooling can result in many hardships and disproportionately affects families of lower socioeconomic status. Current evidence suggests that transmission of SARS-CoV-2, the virus that causes COVID-19, in kindergarten through grade 12 (K–12) schools might not significantly contribute to COVID-19 spread nationwide.”

About 7% to 40% of COVID-19 tests came back positive in the community during the study period of August to November. Face masks were required for all students and staff members at all schools involved in the study. More than 92% of students reportedly complied with masking requirements.

The high rate of face masking, small cohort sizes of up to 20 students and limited contact between cohorts likely helped reduce in-school spread of the coronavirus and could help explain the low levels of transmission, the CDC researchers note. 

“These findings suggest that, with proper mitigation strategies, K–12 schools might be capable of opening for in-person learning with minimal in-school transmission of SARS-CoV-2,” the researchers wrote in their study.