Wastewater surveillance for earlier detection of seniors congregate living COVID-19 outbreaks in Peterborough, Ontario.

The coronavirus disease 2019 (COVID-19) pandemic has disproportionately affected seniors living in congregate living settings. The evolving surveillance context has led to novel use of wastewater surveillance to monitor levels of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in these settings. This study presents a pilot of upstream congregate living wastewater surveillance of SARS-CoV-2 for the detection of COVID-19 outbreaks and the effects of early public health interventions. We monitored localized wastewater SARS-CoV-2 levels from four congregate living settings March 15, 2021 to October 1, 2022 and correlated these levels with suspected and confirmed COVID-19 outbreaks determined by other methods. We identified five wastewater signals that correlated with confirmed outbreaks and three wastewater signals that did not correlate with subsequent outbreaks. In the five confirmed outbreaks, the wastewater signal was detected 2-10 days (median, five days) prior to confirmation of the outbreak by case testing. This pilot demonstrates upstream sampling for SARS-CoV-2 in wastewater may effectively detect outbreaks prior to their detection through symptomatic case testing and could support a balanced approach to outbreak response in congregate living settings, leading to increased wellbeing of these residents.