$1 device developed in Halifax that helps detect COVID-19 in sewers drawing global interest

A $1 device developed at Dalhousie University in Halifax that can help detect COVID-19 in wastewater has been shipped across Canada and around the world to help researchers and public health in the battle against the deadly respiratory illness.

The device is a small, spherical cage that contains an absorbent pad to collect samples from sewer systems. The specimens are then analyzed using lab equipment to determine whether COVID-19 is present in the wastewater.

Unlike previous methods of testing wastewater for COVID-19, the cage — which is 3D-printed at Dalhousie — is inexpensive to make, costing around a dollar.

The low cost of the device makes monitoring more accessible, said Graham Gagnon, one of the researchers and the director of the Dalhousie University Centre for Water Resource Studies. Although the equipment needed to analyze the wastewater is expensive, most COVID-19 testing labs would already have it.

The Dal researchers, including Emalie Hayes, a PhD student who helped develop the device, have shipped about 150 of them to locations as far away as Australia and Sorbonne University in France. Others have been sent to the B.C. Centre for Disease Control, the government of the Northwest Territories and public health bodies in Ontario. 

"We were like, 'Wow, we kind of hit the big time by somebody at the Sorbonne being interested in what we're doing,'" Gagnon said.

The Northwest Territories has used the cage in sewers outside public schools to monitor for COVID-19, and in one case detected an occurrence, he said.

Public Health in Nova Scotia said it does not use wastewater testing to monitor COVID-19.

Predicting the 3rd and 4th waves

Gagnon and his team have been using other devices to monitor four wastewater treatment plants in Halifax, Dartmouth, Mill Cove and Eastern Passage, which process about 92 per cent of the wastewater in the Halifax area.

They've deployed the cages in sewers outside five student residences at Dalhousie, six other locations in the Halifax Regional Municipality (HRM) and a few communities in the province.

They are tested about three times a week, and if one device yields a positive result, the researchers run more frequent tests.

Gagnon said the tests are sensitive enough to detect about three cases of COVID-19 in a population of 100,000, and can reveal the presence of COVID-19 about 10 to 14 days before public health agencies detect it.

When the third wave in Nova Scotia started to take off in the third week of April 2021, the researchers had already been detecting COVID-19 in the wastewater in Halifax since the end of the first week. They saw a huge spike in the presence of COVID-19 at all four wastewater treatment plants at the end of April, just over a week before the number of new daily cases spiked.

The same thing happened as the fourth wave geared up at the end of the summer.

"At the end of August, we were like, 'Oh, that's interesting, we're starting to see a signal again at the wastewater plant.' And then about two weeks later, there was an announcement that they started to see it again," Gagnon said.

Gagnon said he's not able to make predictions about what the fourth wave will look like based on the testing. So far, the pattern is less sustained than what he observed in the third wave, as he's seeing some days with spikes and others without.

He declined to say whether the tests outside the Dalhousie residences have detected an increase in COVID-19 since a large, off-campus student party took place a couple of weeks ago.

'We can cover more people for wastewater testing'

Gagnon said the devices can't pinpoint exactly who may have COVID-19, but they are a quick and easy way to tell whether someone in a defined population has it.

"We can cover more people for wastewater testing than ever could be from sort of clinical testing," he said.

The researchers are now considering other potential applications of the devices, including to detect algal blooms or bacteria such as E. coli.

Meanwhile, New Brunswick company LuminUltra is preparing to sell a product based on the device developed by Gagnon and his team by the end of this month.

Director of product applications, Jordan Schmidt, said there's worldwide interest in the device because it is inexpensive, easy to use and yields a high-quality sample.

"The passive samplers are really good as a smoke detector," Schmidt said. "So, you know, you can set them outside of a long-term care home or a dormitory … where you're mostly concerned, is there COVID-19 or is there not?"