A pioneering surveillance program is already proving its worth in finding virus fragments – and alerting authorities to potential cases.
Wastewater tests for COVID launching in bid to spot outbreaks early
Doug Hendrie 10/09/2020 12:55:40 PM
Wastewater testing should give authorities the ability to notice hotspots early and bring in public health measures accordingly.
Every week, workers are taking samples of wastewater in sewage treatment plants and pumping stations around Australia. These vials will be analysed for traces of the coronavirus that causes COVID-19.
The ultimate goal of the Water Research Australia project ColoSSoS – Collaboration on Sewage Surveillance of SARS-COV-2 – is to accurately detect the presence of the virus in sewage and, ideally, to provide early warning well before people notice symptoms and come in for testing.
People start shedding the virus as early as two days after becoming infected.
For the cost of around $500 per sample, wastewater testing should give authorities the ability to notice hotspots early and bring in public health measures accordingly.
Wastewater testing is most useful when the virus is present at low levels and not self-evident from clinical testing in those same areas, holding out the promise of new ways of keeping the virus as low as possible, in conjunction with tracing, testing and other surveillance methods.
The tests have now been shown to detect the virus even at very low levels; but to help better inform decision-makers, the results gathered to date need to be analysed so the methods can be calibrated in areas of high, medium, low and zero COVID presence.
Victorian Health Minister Jenny Mikakos said in a statement that wastewater testing ‘may be able to give us early warning that coronavirus is in a community and the head start we need for early detection and preventive action’.
Early testing has found traces of the virus in wastewater in regional towns like Apollo Bay in Victoria, Airlie Beach in Queensland and Perisher ski resort in NSW.
The project is most advanced in Victoria, with up to 300 samples a week tested from 25 sites across Victoria. South Australia has also found evidence of the virus in its testing through the project. Other states where the coronavirus is currently present such as New South Wales are at a pilot stage.
Queensland, however, has launched its own pilot standalone program with the University of Queensland and the CSIRO.
Project manager and microbiologist Dr Dan Deere told newsGP the test is proven to work, with thousands of samples now taken in Australia and data analysis and interpretation under way. There are similar programs occurring globally.
‘Sewage testing is very efficient; if you have one infected person shedding the virus amongst thousands, the test should be able to pick that up in one sample,’ he said.
‘You would primarily use it when there are low case numbers or no cases.
‘Our goal is to provide data to COVID-control taskforces at a state level and share the data nationally. It will be used as extra evidence to sit alongside swab testing, antibody testing, data from genotyping to find out if cases are linked, and contact tracing,’ he said.
The test could also give regional towns – where sewage goes through a single treatment plant – the ability to show the virus was not currently present above levels of detection. In major cities, testing has to be done both at large sewage treatment plants as well as suburb-level pumping stations, in order to get more granular detail.
But before it can start feeding usable data into state and federal COVID-control taskforces, the test has to be validated for sensitivity (how often a test correctly finds a result is positive) and specificity (how often a test correctly comes back negative for…
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