Victoria's Covid-19 Response Commander Jeroen Weimar has revealed the main concern health authorities have about the state's most recent outbreak.
The state reported one new locally-acquired Covid-19 case on Saturday and authorities are investigating the source of the infection.
Speaking at a press conference on Saturday, Mr Weimar said people coming forward for testing as soon as they developed symptoms had helped authorities identify "branches" of the outbreak, and urged people to get tested if they felt unwell as testing rates had fallen in recent days.
"I think in the last three or four days where we have lower testing numbers and you're picking up on one or two, that is concerning," he said.
"My personal view is that there is certainly more cases out there. I think we're talking very small numbers.
"But we need to track them down because as we have seen, if we let them linger and build, and we have seen how infectious this Kappa variant can be in certain settings, we really want to get on [top of] the problem."
On Friday, Victoria saw over 15,000 people come forward for testing.
While authorities are working to find the source of the new Covid-19 case reported on Saturday, Mr Weimar said there was a strong reason to believe it will be linked to the Kappa outbreak which has been identified in Melbourne.
Victoria's Health Minister Martin Foley said the new case lives in the city of Melbourne and he praised the case for doing "all the right things".
"From our initial interviews, the individual recognised they had symptoms, got tested, and had a test result, all within the same day, that is, yesterday," Mr Foley said on Saturday.
Mr Weimar said the case was a young man who had "limited excursions outside" and lived with his family.
His three family members were tested on Saturday morning and are awaiting results.
Mr Weimar added there had been "a lot of overlaps" with public exposure sites and cases confirmed to have the Kappa strain.
Calls to 'call out' people not getting tested
Mr Weimar encouraged Victorians to call each other out if they notice a friend, colleague or hospitality worker exhibiting COVID-19 symptoms.
"Call them out in the nicest possible way. Ask them have they had a test," he said.
"That's the collective response we need to see."
Melbourne emerged from two weeks of lockdown on Friday, following a climb in local cases since late May, there are now 74 active cases in the state, including returned travellers in hotel quarantine.
Three new cases were acquired overseas and in hotel quarantine on Saturday.
More to come.
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