On January 26, 2021, this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr). 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.* Discontinuation of in-person schooling can result in many hardships (1) and disproportionately affects families of lower socioeconomic status (2). 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 (3). During August 31-November 29, 2020, COVID-19 cases, spread, and compliance with mask use were investigated among 4,876 students and 654 staff members who participated in in-person learning in 17 K-12 schools in rural Wisconsin. School-attributable COVID-19 case rates were compared with rates in the surrounding community. School administration and public health officials provided information on COVID-19 cases within schools. During the study period, widespread community transmission was observed, with 7%-40% of COVID-19 tests having positive results. Masking was required for all students and staff members at all schools, and rate of reported student mask-wearing was high (>92%). COVID-19 case rates among students and staff members were lower (191 cases among 5,530 persons, or 3,453 cases per 100,000) than were those in the county overall (5,466 per 100,000). Among the 191 cases identified in students and staff members, one in 20 cases among students was linked to in-school transmission; no infections among staff members were found to have been acquired at school. 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. Among 18 selected schools in Wood County, Wisconsin, 17 agreed to participate in this study of COVID-19 in schools and compliance with mask use. One school opted not to participate based on teacher preference. Surveillance was initiated by a small group of physician and medical student researchers. Participating schools were from three public school districts, one private school district, and one independent private school. Eight schools were elementary (grades K-6) with 1,529 students attending in-person, and nine were * Accessed January 13, 2021. https://cai.burbio.com/school-opening-tracker/

ImportanceWith the current COVID-19 return-to-school guidelines, over half of America’s K-12 students are being denied access to full time in-person education, leading to harmful academic, emotional and health consequences.ObjectiveTo describe the specific details of mitigation strategies employed at 17 K-12 schools in Wisconsin during a time of exceptionally high COVID-19 community disease prevalence where in-school transmission was minimal. The aim of this report is to assist school districts and governing bodies in developing full-time return to school plans.DesignRetrospective cohortSettingWood County, Wisconsin, August 31–November 29, 2020Participants5,530 students and staff from 17 schools in 4 school districtsMain outcomes and measuresDistancing between primary and secondary students in schoolSchool ventilation detailsMasking among teachersLunch, recess and bussing practicesResults89.3% of elementary students included in our study did not maintain 6 feet of physical distancing in the classroom and 94.8% were within 6 feet in lunchrooms. The majority of secondary students (86.2%) were able to maintain 6 feet of distancing in the classroom but no students were greater than 6 feet in the hallways. 58.8% of schools did not install new ventilation systems prior to the school year. Students ate lunch indoors. Bussing of students continued and all elementary children were allowed to go without masks at recess.Conclusion and relevanceIn the setting of high community COVID-19 disease transmission, 6 feet of distance between elementary students and major ventilation system renovations in primary or secondary schools do not appear to be necessary to minimize disease spread. Requiring masks at recess and prohibiting bussing also appears unnecessary. These findings may inform guidance on the safe reopening of schools and allow for more children to return to in-person schooling.