Health authorities are concerned there could be more “branches” of infections going undetected in Victoria as testing rates plummeted by half.
The latest case of community infection on Saturday has not been linked to a source and is considered a “mystery” transmission along with seven others of unknown origin.
Testing commander Jeroen Weimar said he was concerned the huge drop in people coming forward for testing could mean there were more infections not being rooted out.
There were just over 15,000 tests on Friday and similar numbers the day before. This is compared to 30,000 to 40,000 daily tests earlier in the outbreak.
“Our concern at the moment is there may well be more people out there, there may well be more branches out there from this outbreak,” said Mr Weimar.
“It is so important now, while we still have restrictions in place, that we identify any other branches that may be there.”
“I think I am concerned the testing numbers are dropping and while we are still dealing with new cases emerging, I would really encourage people to keep those testing numbers up.”
The latest mystery case involved a man living in central Melbourne with his young family.
Mr Weimar asked Victorians to make each other accountable for possible coronavirus symptoms and to encourage each other to get tested.
“Call them out in the nicest possible way,” he said.
There are now 74 active cases in the state, including returned travellers in hotel quarantine.
There are more than 3000 primary close contacts in quarantine as a result of community cases, as well as 122 exposure sites listed on coronavirus.vic.gov.au.
Following a two-week lockdown that ended on Friday, Melburnians are allowed to travel up to 25km from home and meet outside in groups of up to 10 people.
Masks are required indoors and outdoors and hospitality, retail and schools have reopened.
PM: Pandemic origin probe not a blame game
Scott Morrison says a thorough investigation into how the pandemic started is not about apportioning blame but learning how to avoid it happening again.
The Australian prime minister joined G7 leaders to discuss health issues on Saturday in the UK coastal resort of Carbis Bay, with talks focused on the recovery from the pandemic and how the world can be better prepared for an outbreak of other diseases.
“The purpose of these inquiries is to understand – it’s got nothing to do with politics or blame or anything else – it is about understanding it,” Morrison said on Saturday.
“So we all, on a future occasion should it occur, can move quickly and can respond and avoid… the absolute carnage that we’ve seen from this pandemic to both lives and livelihoods all around the world.”
Mr Morrison said more investigations and reforms were necessary to fight potential future pandemics.
“It’s important we have an early warning system, that we have a way to being able to alert the world to when these types of viruses originate and so we can move quickly to stem any transmission,” Mr Morrison.
“The process we called for is not yet done… It is recommending that there be further powers for WHO officers to be able to identify these things early and to ensure that that information is reliably passed on in a timely way.”
The Australian government’s strong support on the international stage for an investigation into how COVID-19 emerged has angered officials in Beijing and further damaged strained relations with China, where the World Health Organisation says the virus was first detected in late 2019.
G7 host UK Prime Minister Boris Johnson and his wife Carrie formally welcomed Mr Morrison to the summit on Saturday afternoon, greeting each other with elbow and lower arm taps.
Mr Morrison also held talks with South Korean President Moon Jae-in and was expected to speak with US President Joe Biden later in the day.