A new study from Australia's national science agency, CSIRO, and the University of Queensland provides further evidence that wastewater (untreated sewage) testing can detect COVID-19 in communities weeks before people display symptoms, suggesting this testing could provide a targeted early detection system as economies re-open and people become more mobile.

This retrospective study looked back at wastewater samples that had been collected in February and early March 2020, in Brisbane, Australia, which were preserved for later analysis.

When analysed for this study, researchers found the archived samples were able to detect the genetic fingerprint of the virus up to three weeks before the first COVID-19 cases were publicly reported through the limited clinical testing available at the time.

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CSIRO chief executive Dr Larry Marshall said wastewater testing is one of the critical science-driven tools that can help open up borders to drive Australia's recovery and reduce future disruption.

"Australians want to do the right thing, but this solution from science detects the disease before people feel the symptoms, so we can outthink and outmanoeuvre this insidious virus," Dr Marshall said.

"It's a true Team Australia approach when states can stay open by targeting their response to contain the disease, saving whole regions from have to shut down; and Team Australia is what we need to grow our way back to recovery."

The study indicated that if sampling is both frequent and widespread enough, the testing can detect the virus before people feel sick, as their bodies start shedding fragments of the virus into the wastewater system through their faeces before they know they're infected.

Director of CSIRO's Australian Centre for Disease Preparedness, Professor Trevor Drew, confirmed that people can become infected and spread (or 'shed') SARS-CoV-2, the virus that causes COVID-19, before they may show any clinical signs.

"Evidence has shown that this virus can infect people and replicate itself for some time before they start showing any symptoms, and some people are entirely asymptomatic but still shed the virus," Prof. Drew said.

"Like many other coronaviruses, SARS-CoV-2 replicates in our digestive system, as well as in our lungs, so can be detected in effluent water a few days before enough people are clinically effected for us to detect the virus in people who are ill."

The researchers have been assisting Queensland Health with their wastewater surveillance program since July 2020, testing sewage for traces of the COVID-19 virus in dozens of locations across Queensland to enhance their response to the pandemic, sharing the results online.

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