Heath authorities believe an Adelaide student diagnosed with coronavirus likely caught the virus while picking up a takeaway pizza.
Health authorities in South Australia have confirmed the high school student picked up a pizza from the Woodville Pizza Bar while two staff working at the restaurant were infectious.
The female student had visited the pizza bar to collect the takeaway order on November 14. She then went to school on Monday, before testing positive for coronavirus on Wednesday night.
Today, South Australia's chief health officer, Professor Nicola Spurrier, said this was "an infectious period" and there were people working at the restaurant at this time who were infected with Covid-19.
Her positive test has sent the entire Woodville High School into lockdown.
South Australia reported two new cases of coronavirus on Thursday, taking the state's total number of active cases to 40.
The new cases are both linked to the growing Parafield cluster, which now has 31 connected cases. The new cases bring the state's total number of cases to 559.
Spurrier said she won't "be pointing a finger of blame" at the student who was diagnosed with Covid-19 last night, and rejected suggestions the student had "done the wrong thing" and should have been isolating when she attended school on Monday.
"Can I just remind people that it took some time for us to get credit card details and all we have been able to do around the Woodville pizza bar is to give social media advice about anybody that has been there," Spurrier said.
"Obviously, not everybody looks at social media, not everyone may have heard that message. I don't think there is any point at all to be pointing a finger or saying somebody is to blame.
"The important thing is if you did get a pizza from that pizza bar and you haven't been tested, now is the time to do so. I can tell you 100 per cent I will back you and I won't be pointing a finger of blame."
Earlier, Victorian authorities announced coronavirus fragments have been detected during wastewater testing in a regional part of the state.
Victoria's acting chief health officer, Professor Allen Cheng, said testing at the Corio treatment plant near Geelong found the viral fragments.
Cheng said the result meant it could be possible an infectious person was in the area.
Locals and visitors to Geelong's northern suburbs, and the town of Lara between November 21 and 23, have been urged to monitor for symptoms and seek out a test if even the mildest symptoms present.
It comes as Victoria celebrated its 27th day without reporting a new coronavirus case.
In Queensland, a police incident at a quarantine hotel has led to almost a dozen officers being forced into isolation after potentially being exposed to Covid-19.
Some 11 police officers have been asked to isolate in hotels or at home after a returned traveller tried to flee their hotel, a Queensland Police spokesperson confirmed to news.com.au.
A police source told 7 News the returned traveller, 41, was suffering from psychosis when they tried to leave the Rydges Hotel Southbank. The man was stopped by police and given a medical assessment.
Police took him back to his hotel and the man later tested positive for Covid-19 on Sunday.
The officers involved have been told to self isolate. Some are quarantining in their homes and others are in the Rydges Hotel Southbank.
A Queensland Police spokesperson said the officers were wearing personal protective equipment at the time of the incident.
"The 11 officers remain in isolation and as of today, all have returned negative tests," the spokesperson said in a statement.
"The Queensland Police Service is conducting welfare checks on the members each day and has been able to make arrangements to ensure adequate staffing is in place while they are isolating."