Detecting the presence of COVID-19 in sewage could become an important tool to monitor the virus and help uncover pockets of infection.

University of Otago geneticist Professor Neil Gemmell is part of a national group led by ESR working to sample wastewater and look for presence of the coronavirus.

“The aim is to monitor the presence, and potentially the abundance, of the virus in our communities. Depending on what we find we could then make some predictions about which communities would be able to come out of lockdown or go back into lockdown because COVID-19 was circulating.

The aim is to monitor the presence, and potentially the abundance, of the virus in our communities

“Ultimately, we would hopefully see the elimination of the virus from our population.”

The COVID-19 project dovetails with an existing international testing programme previously monitoring antibiotic resistance by testing untreated sewage.

Professor Gemmell’s team in the Department of Anatomy has contributed to this study for the past three years by taking samples from Dunedin’s Tahuna wastewater treatment plant.

Urban sewage is of interest to researchers because it allows a wide net to be cast, providing sampling material from a large and mostly healthy population. The testing is also easy to undertake because there are few barriers such as the need to obtain informed consent.

Professor Gemmell believes the protocols used in the existing programme can be transferred successfully to test for COVID-19.

International studies have shown that the virus can be detected in sewage so the next step is to determine the sensitivity of the test and whether the levels of viral load in wastewater correlate with the viral load found in the community from the more routine testing using samples taken via swabbing.

This will involve local testing of both swabs and faecal samples collected from COVID-19 patients and it is hoped this will be under way soon.

We need to do a lot of experimentation to see if it works and then hopefully - in months not days - we would have a system which would enable us to detect the virus quickly, accurately and at scale

“If that pilot work looks promising, we can start to consider using this in a track and trace mode where potentially samples from one waste treatment plant may be enough to give you a good handle on the levels of circulating COVID-19 in a community.

“We need to do a lot of experimentation to see if it works and then hopefully - in months not days - we would have a system which would enable us to detect the virus quickly, accurately and at scale.”

With COVID-19 likely to be present in the community into the future, the ability to test sewage would form part of a surveillance safety net.

Professor Gemmell points out that it could be particularly useful for monitoring likely hot spots for new Covid-19 entry and dispersion such as airports.

“It can add an extra element, perhaps helping to identify virus circulating in asymptomatic carriers. Likely as cases get lower this is where virus may persist and we might determine that, ‘Nobody’s reported sick in this community but there’s still COVID circulating so we have to go in and have a look’.”

In the future the same system may be used as an early-detection network for diseases which have sneaked their way into New Zealand.

“Knowing what else is out there on an ongoing basis could be very helpful from a public health perspective,” Professor Gemmell says.