Ontario researchers increase COVID-19 wastewater sampling

As Ontario heads into a second state of emergency during the COVID-19 pandemic, provincial researchers are expanding the capacity of the province to track and prevent transmission. 

The COVID-19 Wastewater Consortium of Ontario is a provincial initiative that is aimed to develop a wastewater testing infrastructure across Ontario and conduct various tests. The initiative aims to sample wastewater in different municipalities to trace the spread of the virus. This involves collecting and analyzing fecal data, which is more likely to show COVID-19 in asymptomatic individuals than clinical testing. 

Compared to clinical testing, wastewater testing is quicker and more cost-efficient. For example, taking a sample out of a sewage treatment plant from one entire neighbourhood is found to be comparable to the cost of testing one person with a nasal swab.

Furthermore, this testing allows researchers to pinpoint specific neighbourhoods and communities that are being affected through the location of the sewage treatment plant from which samples were taken. This information is extremely crucial in understanding which areas of the city may experience a potential outbreak, allowing officials to employ immediate safety measures within that neighbourhood to prevent further transmission. 

Led by McMaster University’s Gail Krantzberg and Zobia Jawed, both professors at the W Booth School of Engineering Practice and Technology, this project is run by a collective of professionals from a variety of sectors, including sustainability, technology and policy. 

“While testing the population for the presence of the virus is critically important, some carriers of the illness are asymptomatic and don’t get tested. Others get false negatives. Since those infected shed the virus in their feces, testing wastewater captures the reality of COVID-19 in the community,” Krantzberg explained in a McMaster interview

Testing in Hamilton began in fall 2020 and researchers are now increasing sewage sampling to three times per week. The samples are sent to dozens of other cities and universities to be frozen for future testing, as CWCO will continue to collaborate with its partners to establish testing protocols and methodologies.

The tests will be carried out at approximately 13 locations across the McMaster campus, including academic buildings, residences and the McMaster Children’s Hospital. The city of Hamilton has also started collecting sewage samples, as confirmed by city water director Andrew Grice, although public health officials wait to see whether they truly reflect the city’s local cases. 

Other universities such as the University of Guelph, the Ontario Tech University and the University of Ottawa have been testing sewage samples for COVID-19 on a weekly basis. 

“Wastewater-based epidemiology has been used in recent years to monitor the presence of drugs or disease agents in communities. Across the globe, in countries like the Netherlands, Australia and Italy, researchers are finding signs of the SARS-CoV-2 virus in community wastewater samples. These results can augment clinical testing of individuals by public health authorities and potentially serve as an early warning for a second wave of illness,” describes the Canadian Water Network coalition based in Ottawa. 

Although there is the challenge of the wastewater being diluted with rain and other chemicals in the environment, the sampling could be a potential method to tackle the many outbreaks in highly vulnerable populations, such as long-term facilities.

By understanding which facilities may potentially experience an outbreak, officials can tailor their efforts to those specific communities with stronger safety measures and isolation procedures that prevent further transmission.

“A broad wastewater testing system allows us to constantly monitor, test and accurately report on the spread of disease within communities, which would include nursing homes, schools and universities, to address the crucial need not only for the current pandemic but for future outbreaks,” said Krantzberg in a McMaster article. 

If proven to be effective, Ontario’s wastewater sampling could act as an early detection signal of COVID-19, especially in vulnerable communities. Early detection would aid public health experts in implementing quicker safety measures such as isolation, while also informing future reopening plans.

With swift procedures in place, communities will be able to prepare better for a possible outbreak and prevent even further transmission.

Image courtesy of Graphic by Sybil Simpson, Production Coordinator

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