Wastewater Surveillance for SARS-CoV-2 RNA in Canada

Abstract

Wastewater surveillance for SARS-CoV-2 RNA is a relatively recent adaptation of long-standing wastewater surveillance for infectious and other harmful agents. Individuals infected with COVID-19 were found to shed SARS-CoV-2 in their faeces. Researchers around the world confirmed that SARS-CoV-2 RNA fragments could be detected and quantified in community wastewater. Canadian academic researchers, largely as volunteer initiatives, reported proof-of-concept by April 2020. National collaboration was initially facilitated by the Canadian Water Network. Many public health officials were initially skeptical about actionable information being provided by wastewater surveillance even though experience has shown that public health surveillance for a pandemic has no single, perfect approach. Rather, different approaches provide different insights, each with its own strengths and limitations. Public health science must triangulate among different forms of evidence to maximize understanding of what is happening or may be expected. Well-conceived, resourced, and implemented wastewater-based platforms can provide a cost-effective approach to support other conventional lines of evidence. Sustaining wastewater monitoring platforms for future surveillance of other disease targets and health states is a challenge. Canada can benefit from taking lessons learned from the COVID-19 pandemic to develop forward-looking interpretive frameworks and capacity to implement, adapt, and expand such public health surveillance capabilities.

Quantification and Differentiation of SARS-CoV-2 Variants in Wastewater for Surveillance

“…Wastewater surveillance (WS) has been an excellent alternative to monitor the scope of the COVID-19 pandemic in a community and is complementary to clinical testing for guiding public health measurements . Studies have shown that SARS-CoV-2 RNA in wastewater can appear 4–10 days prior to clinical PCR test results .…”

“…Many countries have utilized metagenomic sequencing of SARS-CoV-2 RNA from wastewater samples to obtain high resolution sequence information and identify emerging and dominant variants in a specific community . Sequencing enables the identification of new and unique mutations that are used as targets in RT-qPCR to reveal information about the presence of specific variants. , With this sequencing information several variant-specific singleplex RT-qPCR assays have been developed and applied for the identification of Alpha, Beta, Gamma, or Delta in wastewater. ,, However, the RNA is present in wastewater at low concentration and fragmented, and consists of a mixture of SARS-CoV-2 variants, resulting in tremendous technical challenges with detection and reassembly of viral genomes from wastewater . Furthermore, sequencing approaches are time-consuming, expensive, and inaccessible in many countries with limited resources.…”

“…Wastewater surveillance (WS) has been an excellent alternative to monitor the scope of the COVID-19 pandemic in a community and is complementary to clinical testing for guiding public health measurements. 2 Studies have shown that SARS-CoV-2 RNA in wastewater can appear 4–10 days prior to clinical PCR test results. 2 WS can provide a realistic scale of the pandemic because it can capture input from all the symptomatic, presymptomatic, and asymptomatic individuals in a whole community served by a common sewer system.…”

“… 2 Studies have shown that SARS-CoV-2 RNA in wastewater can appear 4–10 days prior to clinical PCR test results. 2 WS can provide a realistic scale of the pandemic because it can capture input from all the symptomatic, presymptomatic, and asymptomatic individuals in a whole community served by a common sewer system. This alternative approach for assessing the status of overall community infection of SARS-CoV-2 has been supported by various organizations such as the U.S. Centers for Disease Control and Prevention, the International Water Association, the Global Institute for Water Security, the Public Health Agency of Canada, and the Canadian Water Network.…”

“… 2 , 12 With this sequencing information several variant-specific singleplex RT-qPCR assays have been developed and applied for the identification of Alpha, Beta, Gamma, or Delta in wastewater. 2 , 13 , 14 However, the RNA is present in wastewater at low concentration and fragmented, and consists of a mixture of SARS-CoV-2 variants, resulting in tremendous technical challenges with detection and reassembly of viral genomes from wastewater. 2 Furthermore, sequencing approaches are time-consuming, expensive, and inaccessible in many countries with limited resources.…”