arly in the pandemic, schools closed across Canada to help reduce the circulation of SARS-CoV-2 and decrease risks associated with infection among staff and students. 1 Evidence has since suggested that school closures and decreased in-person learning have had negative impacts on the mental health, well-being, educational attainment, social connection, health care access and health behaviours of students, families and staff. [1][2][3][4][5][6][7][8][9][10][11][12] Combined with high socioeconomic tolls, [13][14][15] these unintended consequences have compelled consideration of the efficacy of school closures in limiting morbidity and mortality associated with the COVID-19 pandemic.Evidence now indicates that age is a risk factor for severe disease and children typically experience a mild course of illness. [16][17][18][19][20][21][22] There is also a growing body of literature suggesting that children's in-person school attendance may not be an important driver of transmission; contact-tracing and test-based studies from other jurisdictions have identified little or no transmission in the school setting. [23][24][25][26][27][28][29][30][31][32][33][34] Internation-ally, studies illustrate that school reopening has not affected numbers of pediatric cases 23,35,36 and that the risk of SARS-CoV-2 infection has not increased for educational staff working with children. 30,36,37 There are limited peer-reviewed data in Canada regarding risk of SARS-CoV-2 transmission in schools, although Ottawa Public Health has reported low rates of school-based transmission. 38 Given that transmission risk is influenced by community-level epidemiology, public health measures, health system infrastructure and other jurisdictional factors, this study contributes needed evidence within the Canadian

ObjectivesFew studies reported COVID-19 cases in schools during the 2020/21 academic year in a setting of uninterrupted in-person schooling. The main objective was to determine the SARS-CoV-2 seroprevalence among school staff in Vancouver public schools.DesignCumulative incident COVID-19 cases among all students and school staff based on public health data, with an embedded cross-sectional serosurvey among a school staff sample that was compared to period, age, sex and geographical location-weighted data from blood donors.SettingVancouver School District (British Columbia, Canada) from kindergarten to grade 12.ParticipantsActive school staff enrolled from 3 February to 23 April 2021 with serology testing from 10 February to 15 May 2021.Main outcome measuresSARS-CoV-2 seroprevalence among school staff, based on spike (S)-based (unvaccinated staff) or N-based serology testing (vaccinated staff).ResultsPublic health data showed the cumulative incidence of COVID-19 among students attending in-person was 9.8 per 1000 students (n=47 280), and 13 per 1000 among school staff (n=7071). In a representative sample of 1689 school staff, 78.2% had classroom responsibilities, and spent a median of 17.6 hours in class per week (IQR: 5.0–25 hours). Although 21.5% (363/1686) of surveyed staff self-reported close contact with a COVID-19 case outside of their household (16.5% contacts were school-based), 5 cases likely acquired the infection at school based on viral testing. Sensitivity/Specificity-adjusted seroprevalence in 1556/1689 staff (92.1%) was 2.3% (95% CI: 1.6% to 3.2%), comparable to a sex, age, date and residency area-weighted seroprevalence of 2.6% (95% CI: 2.2% to 3.1%) among 5417 blood donors.ConclusionSeroprevalence among staff was comparable to a reference group of blood donors from the same community. These data show that in-person schooling could be safely maintained during the 2020/21 school year with mitigation measures, in a large school district in Vancouver, Canada.

Background: There is an urgent need to assess the role of schools in the spread of SARS-CoV-2 in Canada to inform public health measures. We describe the epidemiology of SARS-CoV-2 infection in students and staff in the Vancouver Coastal Health (VCH) region in the first three months of the 2020/2021 academic year, and examine the extent of transmission in schools. Methods: This descriptive epidemiologic study using contact tracing data included all SARS-CoV-2 cases reported to VCH between September 10 and December 18, 2020 who worked in or attended K-12 schools in-person. Case and cluster characteristics were described. Results: There were 699 school staff and student cases during the study period, for an incidence of 55 cases per 10,000 population, compared to 73 per 10,000 population in all VCH residents. Among VCH resident staff and student cases, 53% were linked to a household case/cluster, <1.5% were hospitalized and there were no deaths. Out of 699 cases present at school, 26 clusters with school-based transmission resulted in 55 secondary cases. Staff members accounted for 54% of index cases (14/26) while comprising 14% of the school population. Among clusters, 88% had fewer than 4 secondary cases. Interpretation: COVID-19 incidence in the school population was lower than that of the general population. There were no deaths and severe disease was rare. School-based transmissions of SARS-CoV-2 were uncommon and clusters were small. Our results support the growing body of evidence that schools do not play a major role in the spread of SARS-CoV-2.