When virus fragments of Covid-19 were found in raw sewage in Sydney - and Covid testing rates had dropped - it sparked a renewed call from NSW Health yesterday for people in the Hawkesbury and South Western Sydney region to step up and get tested.

Lismore sewage

While we have had no new Covid-19 cases for weeks now in the Lismore area, would a raw sewage testing program be of benefit to our community into the future as an early warning system that the virus is spreading?

The Lismore App asked Lismore City Council if there were plans to introduce any testing of the sewage in our area and was told “we don’t do it and don’t have the capability to do so”.

SARS-CoV-2

The sewage testing in Sydney for molecular markers of SARS-CoV-2 - the virus that causes Covid-19 - began in July as part of a new research program by NSW Health and Sydney Water.

Sydney Water’s General Manager Customer, Strategy and Engagement, Maryanne Graham said virus fragments in sewage can mean that there are active cases in the catchment area.

“But people can continue to ‘shed’ virus genetic material for some weeks after recovery,” Ms Graham said. “Our wastewater network can provide data to help the health response to the pandemic."

NSW Chief Health Officer Kerry Chant said the research was still in “early days”, but was “one more way we can strengthen our fight against Covid-19”.

“This is a program that will show us where COVID-19 has been. For instance, we would expect to see viral fragments in Sydney sewage where we have consistently had cases in the community or in hotel quarantine.

“However, if we continue to have very few active cases, there is scope for this testing to provide early warning in places without known or recent cases.”

Treatment plants

Ms Graham said there is no evidence COVID-19 is transmitted via wastewater systems.

“The virus is susceptible to current treatment processes which are effective in deactivating the virus and there is no risk to the public or to staff who are trained to complete this testing,” she said.

Yesterday’s call for Sydney residents to get tested came after the sewage surveillance program detected fragments of the virus at the North Richmond and West Camden treatment plants.

The most recent cases in the West Camden catchment were reported in September, but no one living in the North Richmond catchment has recently tested positive for COVID-19.

Sydney Water laboratories commenced testing raw sewage from plants at Bondi, Malabar, North Head, Cronulla, St Marys, Quakers Hill, Rouse Hill, Penrith, Shellharbour and Winmalee in the Blue Mountains about two weeks ago.

The first round of samples found positive results at Bondi, Malabar, and Winmalee. Further sampling and analysis are required to assess the significance of this initial positive result.