key: cord-0712162-blvmk962 authors: Dawson, P.; Worrell, M. C.; Malone, S.; Fritz, S. A.; McLaughlin, H. P.; Montgomery, B. K.; Boyle, M.; Gomel, A.; Hayes, S.; Maricque, B.; Lai, A. M.; Neidich, J. A.; Tinker, S. C.; Lee, J. S.; Orscheln, R. C.; Tong, S.; Charney, R.; Rebmann, T.; Mooney, J.; Rains, C.; Yoon, N.; Petit, M.; Towns, K.; Goddard, C.; Schmidt, S.; Barrios, L. C.; Neatherlin, J. C.; Salzer, J. S.; Newland, J. G.; Coordination, COVID-19 Response Fieldwork and Laboratory Teams AND Missouri School District Data and title: Modifications to student quarantine policies in K-12 schools implementing multiple COVID-19 prevention strategies restores in-person education without increasing SARS-CoV-2 transmission risk, January-March 2021 date: 2022-03-21 journal: nan DOI: 10.1101/2022.03.18.22272631 sha: bb523e8d45ce728ae6af5792390c5900c6968ccc doc_id: 712162 cord_uid: blvmk962 Objective : To determine whether modified K-12 student quarantine policies that allow some students to continue in-person education during their quarantine period increase schoolwide SARS-CoV-2 transmission risk following the increase in cases in winter 2020-2021. Methods : We conducted a prospective cohort study of COVID-19 cases and exposures among students and staff (n=65,621) in 103 Missouri public schools. Participants were offered free, saliva-based RT-PCR testing. An adjusted Cox regression model compared hazard rates of school-based SARS-CoV-2 infections between schools with a modified versus standard quarantine policy. Results : From January-March 2021, a projected 23 (1%) school-based transmission events occurred among 1,636 school close contacts. There was no difference in the adjusted hazard rates of school-based SARS-CoV-2 infections between schools with a modified versus standard quarantine policy (hazard ratio=1.00; 95% confidence interval: 0.97-1.03). Discussion : School-based SARS-CoV-2 transmission was rare in 103 K-12 schools implementing multiple COVID-19 prevention strategies. Modified student quarantine policies were not associated with increased school incidence of COVID-19. Modifications to student quarantine policies may be a useful strategy for K-12 schools to safely reduce disruptions to in-person education during times of increased COVID-19 community incidence. 6 119 positive test specimen), school officials conducted contact tracing to identify their school-based 120 close contacts. A close contact was defined as someone who was ≤6 feet away from a person 121 with COVID-19 for ≥15 minutes in one 24-hour period. In districts A-C, school officials 122 determined if student close contacts (hereafter, contacts) met criteria for a modified quarantine. 123 School officials followed everyone through completion of their isolation or quarantine period, 124 including whether contacts received a positive NAAT or antigen test. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. 7 142 collected from persons with COVID-19 soon after recruitment and from contacts 5-14 days after 143 their last school-based exposure. Specimens were tested for SARS-CoV-2 by real-time reverse 144 transcription polymerase chain reaction (RT-PCR) as previously described. (12) Full genome 145 sequences were generated from RT-PCR-positive saliva specimens at CDC (20) . 147 For each school-based contact who received a positive test result from the enhanced 148 investigation or elsewhere reported to school officials, we conducted a case determination 149 process to assess the likelihood of the infection being from school-based transmission. Infections 150 were classified as probable, possible, or unlikely school-based transmission using epidemiologic 151 and sequencing data from case-contact pairs. School-based transmission was considered unlikely 152 if the close contact lived in the same household as another person with COVID-19 ≤14 days 153 before symptom onset or date of collection of their first positive specimen; their exposure, 154 symptom, or testing timeline was not consistent with the known epidemiology of COVID-19; or 155 the sequence generated from their specimen had >5 single nucleotide polymorphisms (SNPs) 156 compared to the sequence generated from their school-based index case's specimen. School-157 based transmission was considered possible if the close contact had non-household community 158 exposure to a person with COVID-19 ≤14 days before symptom onset or date of collection of 159 their first positive specimen and was considered probable if their only identified close contact 160 was with the school-based person with COVID-19. If the sequence generated from the close 161 contact's specimen had ≤5 SNPs compared to the sequence generated from their school-based 162 index case's specimen, it was classified as probable school-based transmission. Classifications 163 were made by at least two members of the investigation team. Discordant classifications were for use under a CC0 license. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The percentage of asymptomatic contacts we tested who received a positive test result was 182 extrapolated to contacts who were never tested to project the total number of cases (contacts who 183 did not receive testing were presumed to be asymptomatic). Schoolwide COVID-19 crude 184 incidence rates and Cox proportional hazard rates (using observed and projected total case 185 numbers) were compared between schools with a modified versus standard quarantine policy. 186 The approximate number of students and staff at each school whose attendance was 100% virtual for use under a CC0 license. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Table) . This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. 288 ‡ Includes 7 contacts who were also ineligible due to extracurricular activities and 2 contacts who were also 289 ineligible due to contact outside of school. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 21, 2022. ; https://doi.org/10.1101/2022.03.18.22272631 doi: medRxiv preprint 21 308 4.00 per 100,000 per week in schools following standard quarantine (P=0.24). The adjusted 309 hazard rates of school-based SARS-CoV-2 infections were not different between schools that 310 implemented a modified quarantine policy and schools that did not when using observed cases or 311 total projected cases (for both, hazard ratio, HR=1.00; 95% confidence interval, CI: 0.97-1.03). 312 The adjusted probability of school-based SARS-CoV-2 infections based on total projected cases 313 reached a maximum of 0.83% (95% CI: 0.75-0.91%) by the end of the study (Fig 2) . 318 Caption: Top-right inset shows zoomed-in view of adjusted probability curves over the study period. The adjusted* 319 probability curve of school-based SARS-CoV-2 infection in schools with a standard quarantine policy is shown by 320 the teal line; in schools with a modified quarantine policy, it is shown by the dotted black line. The adjusted 321 probability curves and 95% confidence intervals were the same for schools with and without a modified quarantine 322 policy. 323 * The Cox regression model was adjusted for potential school-level confounding factors: quartiles of the percentage 324 of students eligible to receive free or reduced-price lunch (as a proxy for school resources) and the school's total 325 number of cases that attended school or a school-related event during the study period. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. S1 Fig describes the mitigation strategies being utilized in the schools. Virtual instruction 197 was offered by 92% of schools, universal masking policies (face masks required for all students, 198 teachers, staff, and visitors on school grounds) were implemented in 97% of schools, 94% of 199 schools reported efforts to increase ventilation in classrooms but this report 334 demonstrates this in urban, suburban, and rural public school districts; in elementary, middle, 335 and high school grades; in schools that have implemented a modified quarantine and those that 336 have not; during periods of moderate-to high-community incidence (21, 22); and for a combined 337 estimated school population of >65,000 students, teachers, and staff Levels(8), implementation of layered COVID-19 It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted Second, we did not test all 361 identified contacts for SARS-CoV-2 following exposure, and therefore the observed number and 362 incidence of school-based SARS-CoV-2 infections is possibly an underestimation. However, underestimation. Third, due to low variability in school-level prevention strategies and 366 the low number of identified school-based transmission events, analyses of the effect of specific 367 prevention strategies on SARS-CoV-2 transmission were underpowered. Fourth, sequencing data 368 and interview data were not available for all identified school index case-positive contact pairs, 369 and in these instances, all persons who received a positive test result during the 14-day window 370 were presumed to have been infected in school. For the six contacts with a positive test result 371 who had paired sequencing data In this two-month investigation of SARS-CoV-2 transmission in 103 schools implementing 377 layered COVID-19 prevention strategies and modifications to quarantine policies, school-based for use under a CC0 license It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted SARS-CoV-2 transmission was rare and schools that implemented a modified quarantine policy 379 did not have greater incidence of school-based SARS-CoV-2 infections. Given these findings 380 and the benefits of restoring in-person learning for students, schools implementing multiple investigation Note: Data are from surveys completed by school and district officials unless otherwise noted It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted Abbreviations: COVID-19 = coronavirus disease K-12 = kindergarten through grade 12 RR = relative risk Surveyed ventilation strategies included opening doors when possible, opening windows when possible, using fans 411 to circulate air, and updating heating, ventilation, and air conditioning Abbreviations: COVID-19 = coronavirus disease HVAC = heating, ventilation, and air conditioning * School buildings also include the areas listed in the subsequent two categories: hallways, stairways, gymnasiums, 421 cafeterias, and other special use rooms. for use under a CC0 license It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted COVID-19 School Fieldwork Team It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity Data and policy to guide opening schools safely to limit the spread of SARS-CoV-2 infection K-12 Virtual Schooling, COVID-19, and Student Success Advocating for Children During the COVID-19 School Closures Demographic Trends of People Receiving COVID-19 Vaccinations in the United States 2022 Vaccine Hesitancy for COVID-19: County and local estimates 2021 Increasing COVID-19 Vaccine Uptake among Members of Racial and Ethnic Minority Communities: A Guide for Developing, Implementing, and Monitoring Community-Driven Strategies It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted Pilot Investigation of SARS-CoV-2 Secondary Transmission in Kindergarten Through Grade 12 Transmission in Elementary Schools -Salt Lake County COVID-19 Cases and Transmission in 17 K-12 Schools -Wood County Transmission of SARS-CoV-2 in Australian educational settings: a prospective cohort study. The Lancet Child & Adolescent Health It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted Clusters of SARS-CoV-2 Infection Among Elementary School Educators and Students in One School District -Georgia County Health Department. Quarantine and Isolation County Department of Public Health. Home Quarantine Instructions for Close Contacts to People With COVID-19 2021 Rapid, sensitive, fullgenome sequencing of severe acute respiratory syndrome coronavirus 2. Emerging Infectious Diseases County Health Department. COVID-19 Dashboard: Springfield Centers for Disease Control and Prevention. Trends in Number of COVID-19 Cases and Deaths in the US Reported to CDC, by State/Territory 2022 All the students, families, educators, nurses, administrators, and staff members from participating schools and school districts in Greene This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted March 21, 2022. ; https://doi.org/10.1101/2022.03.18.22272631 doi: medRxiv preprint