Association of Learning Model With COVID-19 Incidence Among Public School Eligible Children in Salt Lake City, Utah, June-November 2020

Abstract

To the Editor—Although growing evidence indicates that SARS-CoV-2 transmission in schools is infrequent, especially among younger students [1–3], questions remain about risks across age levels. Salt Lake County, Utah includes 5 public school districts and local school boards determined the Fall 2020 learning model. Four districts returned to in-person learning with prevention strategies, including required masking and an option for remote learning [4, 5], while a fifth solely utilized remote learning. To better understand the risk of in-person learning on COVID-19 incidence and to help school leaders guide policies, we compared COVID-19 incidence in school-aged children among districts. We identified confirmed COVID-19 cases reported to the Utah Department of Health during August 13-November 9, 2020, in children aged 5-17 years, categorized by school-age levels: elementary (5-10 years), middle (11-13 years), or high school (14-17 years). The home address for each reported case was geocoded to residence in each district. Four districts were in-person; one was remote. The relative risk (RR) for districts was compared using incidence for in-person districts divided by incidence in the remote district. The incidence rates were calculated by comparing cases in school-aged children to the total number of school-aged persons in the public school districts expressed per 100 000. During the study period, there were 3787 COVID-19 cases for in-person school districts and 410 in the remote district. The overall incidence was 2361/100 000 school-aged persons for in-person districts and 1999/100 000 school-aged persons for the remote district for a RR of 1.18, when comparing in-person districts to the remote district (Table 1). When stratified by age, the RR for elementary and middle school-aged persons residing in in-person districts did not differ from those in the remote district (Table 1). However, COVID-19 incidence was higher for high school-aged persons residing in the in-person districts, as compared to the remote district (RR: 1.61 [1.40-1.85]). Our findings align with recent reports showing in-person learning is not associated with substantial excess risk, especially in younger ages when prevention strategies, including universal masking, are used. Without these interventions in place, transmission in children can be very high, as evidenced by experiences in other congregate environments such as athletics and camps [6, 7]. The 60% higher risk associated with residing in the in-person districts for high school-aged persons requires further investigation and aligns with prior studies on high school-aged populations [8]. Although the requirements for prevention strategies in Utah high schools did not differ between elementary and middle schools, enforcement may have been less effective with their larger student populations and in-school mobility. Attending school in-person may also have influenced higher engagement in out-of-school social activities that promote transmission. Of note, however, all districts, including the remote district, offered extracurricular activities, including athletics, during the study period. Additionally, despite lower incidence during the study period, the baseline incidence in the remote learning district was higher at the beginning of the school year indicating that this difference emerged after school opening (Table 1). Differences in demographics that are associated with risk for infection between the districts could have contributed to our findings. However, the remote learning district has a higher percentage of students with non-White race and applyparastyle “fig//caption/p[1]” parastyle “FigCapt”