Early identification of a COVID-19 outbreak detected by wastewater surveillance at a large homeless shelter in Toronto, Ontario

• Published in: Canadian journal of public health Vol. 114; no. 1; pp. 72 - 79
• Main Authors: Akingbola, Samantha, Fernandes, Reisha, Borden, Susan, Gilbride, Kimberley, Oswald, Claire, Straus, Sharon, Tehrani, Amir, Thomas, Janis, Stuart, Rebecca
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.02.2023; Springer Nature B.V
• Subjects: Communication; Coronaviruses; COVID-19; COVID-19 - epidemiology; COVID-19 vaccines; Disease Outbreaks; Genetics; Health surveillance; Homeless people; Homelessness; Humans; Ill-Housed Persons; Immunization; Intervention; Male; Medicine; Medicine & Public Health; Ontario - epidemiology; Outbreaks; Physicians; Pipe cleaning; Population; Populations; Public Health; SARS-CoV-2; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Shelters; Solid phases; Special Section on COVID-19: Innovations in Policy and Practice; Surveillance; Tests; Vaccination; Viral diseases; Viruses; Wastewater; Wastewater-Based Epidemiological Monitoring; Water sampling; Ontario; Toronto Ontario Canada; Canada; Ontario Canada; COVID-19; Vulnerable populations; eaux usées; Wastewater; Public health; populations vulnérables; santé publique
• DOI: 10.17269/s41997-022-00696-8
• ISSN: 0008-4263; 1920-7476

Setting Toronto (Ontario, Canada) is a large urban centre with a significant population of underhoused residents and several dozen shelters for this population with known medical and social vulnerabilities. A sizeable men’s homeless shelter piloted a facility-level SARS-CoV-2 wastewater surveillance program. Intervention Wastewater surveillance was initiated at the shelter in January 2021. One-hour composite wastewater samples were collected twice weekly from a terminal sanitary clean-out pipe. The genetic material of the SARS-CoV-2 virus was extracted from the solid phase of each sample and analyzed using real-time qPCR to estimate the viral level. Wastewater results were reported to facility managers and Toronto Public Health within 4 days. Outcomes There were 169 clients on-site at the time of the investigation. Wastewater surveillance alerted to the presence of COVID-19 activity at the site, prior to clinical detection. This notification acted as an early warning signal, which allowed for timely symptom screening and case finding for shelter managers and the local health unit, in preparation for the declaration of an outbreak. Implications Wastewater surveillance acted as an advanced notification leading to the timely deployment of enhanced testing prior to clinical presentation in a population with known vulnerabilities. Wastewater surveillance at the facility level is beneficial, particularly in high-risk congregate living settings such as shelters that house transient populations where clinical testing and vaccination can be challenging. Open communication, established individual facility response plans, and a balanced threshold for action are essential to an effective wastewater surveillance program.