SARS-CoV-2 transmission in K-12 schools in the Vancouver Coastal Health Region: a descriptive epidemiologic study (preprint)

ABSTRACT

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.