COVID-19 in the urban built environment (CUBE): Evaluating the use of environmental swabs for the detection and surveillance of SARS-CoV-2 in school and congregate settings

Surveillance for SARS-CoV-2 in populations and the environment has been a critical component of our public health toolbox throughout the COVID-19 pandemic response. Ottawa pioneered the use of environmental surveillance, through wastewater signals, to predict COVID-19 disease burden in the community and inform the local public health response at a broad level. Building on previous work in hospitals, our study team addresses an important gap in surveillance: schools, childcare and long-term care settings. Most children and youth with COVID-19 will have few or no symptoms, yet they could still face considerable disruption to learning and potential hospitalization for their illness. Conversely, the risk of morbidity and mortality is highest in the older frail adult population. Testing for COVID-19 has been recommended to break chains of transmissions in classroom cohorts and congregate living settings. Yet testing students remains challenging because of difficulties in accessibility, acceptability of sampling methods, and the ability to screen low-risk students in schools serving communities with high rates of COVID-19. In long-term care, there is additional concern of waning immunity among staff and residents who were vaccinated more than six months ago, increasing residents' vulnerability to infection from asymptomatic or mildly symptomatic individuals. Our method of environmental sampling of floors could improve upon the spatial resolution of wastewater surveillance while focusing human testing only where it is needed. We will draw from vaccination rates to also provide insights into the SARS-CoV-2 environmental burden in a vaccinated population (such as high schools, long-term care), as testing criteria may evolve and no longer reflect infection prevalence, and at a finer spatial scale than conventional wastewater sampling.