New South Wales has recorded a local COVID-19 case, ending the state's 17-day streak of zero new community infections.
Health authorities are rushing to ascertain how the man in his 50s from Sydney's eastern suburbs contracted the virus, given he has not recently been overseas and is not a healthcare, border, or quarantine worker.
The man visited a number of locations between Friday, 30 April, and Sunday, 2 May, while infectious.
These included Event Cinemas and the Meat Store at Bondi Junction, Barbeques Galore in Annandale and Casula, Joe's Barbeques and Heating and Tucker Barbeques in Silverwater, BP in Mascot and Figo Restaurant in Rushcutters Bay.
Anyone who attended these venues at the times listed on the is being asked to isolate immediately and undergo a COVID-19 test.
Urgent genome sequencing is underway to determine if the strain of the virus is linked to any interstate cases or infections in hotel quarantine, with results expected within 24 hours.
“This person did everything right, but it goes to show we can’t take anything for granted,” NSW Premier Gladys Berejiklian told reporters on Tuesday.
"Our job now is to get on top of it, to identify any other potential cases, try to identify the source, and make sure we get on top of this case."
Chief Medical Officer Kerry Chant said the "usual routes where we would expect someone to have acquired the infection", such as contact with a hospital, did not apply in this case.
The man also had a high viral load suggesting he was potentially highly contagious, which Dr Chant said was "cause for concern".
"But we are also really interested in how this person acquired the infection to understand the broader risk to the community," she said.
The man has a "reasonable number" of close contacts, who are being tested to identify any other possible chains of transmission.
NSW Chief Health Officer Dr Kerry Chant. Source: AAP
"I hope that everyone takes this as a wake-up call," Ms Berejikian said.
"We need to be aware that virus is still around. Whilst in a pandemic we still have to maintain that level of caution."
Responding to the new case, which will appear in Thursday's figures, federal Health Minister Greg Hunt said the NSW contact tracing system was the "absolute global gold standard".
NSW Health said late on Wednesday it had been notified fragments of the virus had been detected in the Marrickville sewage network.
The catchment includes about 42,000 people and takes sewage from many suburbs in Sydney’s inner west.
NSW Health said people from the affected suburbs, which can be found on the department's website, should be vigilant in monitoring for symptoms, and get tested and isolate if they appear.
