Sewage being tested for coronavirus in 8 countries—but not Canada

Beginning in early May, researchers in Paris were already detecting coronavirus in the sewers under the city.

There were only 91 cases of coronavirus in Paris that doctors knew about on March 5 and researchers saw that the increase in cases could be detected in the city’s wastewater, according to Global News.

Paris began its lockdown on March 17 and was successful in flattening the city’s curve. This could be seen in human testing and in sewage testing. Rates of the virus had continued to increase in the sewage and reached the peak on April 9.

Bernadette Conant of the Canadian Water Network said, “The thing that’s really important about the French study … is that the trends in the wastewater tend to match what you see in the community.”

When people are infected with coronavirus it can take some time before they are present in statistics—if ever. They have to start showing symptoms, look for testing, get tested if they can and then await results before ever showing up in statistics.

Well before that, people begin leaving traces of the virus in the sewage which means coronavirus may be tracked much more quickly and efficiently when testing sewage and not just individuals.

“They actually saw it in a city of 12 million people when there were no deaths yet and only 91 clinical cases at that point,” Conant said.

“They could see both the cases rising and the amount of COVID in the community rising before that sort of steep rise in the amount of cases, or deaths, occurred. After lockdown, they saw what one would expect if this was a good indication of circulation of prevalence of COVID in the community — it started to trend down.”

Many economies have been hit hard by the virus due to lockdown measures and governments are feeling the pressure to reopen. History shows that when this happens, there is usually a second wave on the way.

“If you think your communities have flattened the curve, do those curves stay flat when we reopen?,” Conant said. “Ideally what you want in these cases of reopening the economy is a canary in the mine shaft to tell you when it’s starting to spread again, or when it’s come back.”

Testing sewage may be a much quicker and more accurate way to find out coronavirus information that is needed. The Public Health Agency of Canada says that so far there is not a government in the country looking to analyze sewage to find information on the virus.

“The Public Health Agency of Canada has been engaging with a range of stakeholders to assess current activities related to wastewater sampling including testing and sampling,” said spokesperson Natalie Mohamed in an email. “An evidence review is underway to better understand the scientific merits of this approach and learn from any successful initiatives undertaken to date.”

“Research on testing sewage and wastewater is at an early stage of development. At this time, PHAC is not aware of any Canadian studies collecting sewage samples for the detection and identification of COVID-19.”

Conant says a “pan-Canadian surveillance system,” would be ideal.

Sewage was tested in Brisbane, Australia throughout March and April showing results that came close to coronavirus rates in human testing.

There were similar results in Israel where scientists found higher levels of coronavirus in Tel Aviv—a known hotspot.

Similar techniques are being used by the United States as well as the Netherlands. Dutch scientists detected the virus only four days after a case was first reported there. In March they were able to see the virus appear almost in real time.

In Houston, Texas officials began weekly tests for coronavirus in the sewage. They plan to find out roughly how many people have coronavirus but are asymptomatic as well as find local hotspots that are still unknown.

Conant noted that there are eight countries testing sewage or the virus—that she knows about.

There are currently 99 coronavirus research projects being federally funded in Canada though none involve wastewater testing.

Conant says that in an ideal situation, testing would be on an institutional level with schools and long-term care homes being tested.

“Definitely that potential is there. The potential is there, but we’re not there,” she said.

“What’s an ideal situation is that we have a surveillance network where all these facilities regularly submit samples for testing. That’s what everybody wants to build towards.”