Victorian authorities are yet to find any evidence a COVID-infected nurse has passed on the virus to patients and healthcare colleagues at two Melbourne hospitals.
Acting Premier James Merlino confirmed the one new locally acquired case reported on Friday was linked to Southbank's Kings Park Apartment Complex.
The woman is a household contact of an existing case, bringing the outbreak at the locked-down CBD complex to nine cases.
Of the 199 residents bunkered down in isolation, 158 have returned negative tests to date including 19 from a sensitive corner of the complex where all cases have emerged.
Victoria's testing commander Jeroen Weimar said authorities were also buoyed by a set of negative results from hospital staff and patients potentially exposed to coronavirus by an "operational error".
A nurse who had been treating the state's three hospitalised COVID-19 cases at Epping Private Hospital also worked two days last week at Epping's Northern Hospital, while possibly infectious.
Victorian healthcare staff working on a COVID ward and dealing directly with virus patients must attest they are not doing shifts across multiple sites.
But Mr Weimar holds Epping Private Hospital accountable for the mistake rather than the nurse.
"It would appear there has been a lack of control over the rostering system. They understand that and what they need to do," he told reporters on Friday.
Twenty-four of 30 Epping Private Hospital staff and 55 of 67 people at the Northern Hospital have returned negative tests so far after being identified as close contacts.
The nurse also visited Northern Hospital's vaccination centre on Monday for her final dose of the COVID-19 vaccine, forcing another 62 people into isolation for two weeks.
All seven staff have tested negative along with half of the 55 patients.
It remains unclear how the nurse caught the virus, with genomic sequencing results expected back as early as Friday afternoon.
It comes as the national COVID spotlight has shifted across the Murray River, with Chief Health Officer Brett Sutton declaring three Sydney areas "orange zones" under Victoria's permit system.
Those planning to enter Victoria from the City of Sydney, Waverley and Woollahra council areas must now obtain a travel permit, get tested and isolate until they receive a negative result.
Mr Merlino said the Sydney outbreak was a "sobering reminder that this virus is with us in our country and will be with us for quite some time".
Meanwhile, Professor Sutton is facing criticism after flying to Canberra for a two-day National Health and Medical Research Council meeting, which coincided with an awards ceremony on Wednesday night.
Mr Merlino said the chief health officer attended the event in a work capacity and travelled within the rules.
"He's entitled to go there," he told reporters on Friday.
Department of Health secretary Euan Wallace later told a parliamentary inquiry the trip was taxpayer-funded as Prof Sutton was working on state health business.
Federal Health Minister Greg Hunt, who was also at the awards evening, had no issue with Prof Sutton's actions.
"That story was deeply unfair," he told ABC Melbourne radio.
But Victoria's opposition health spokeswoman Georgie Crozier questioned the optics, given the ban on home visitors in Melbourne at the time.
That ban, along with Melbourne's 25km travel limit and outdoor mask mandate, was scrapped as restrictions eased across the state.
Under the latest raft of rule changes from 11.59pm on Thursday, Melbourne residents can now host two adult visitors into their homes per day and gather outdoors in groups of 20.
Masks are no longer required outdoors either, while businesses such as gyms and indoor entertainment can reopen.
A negative test requirement for Melburnians heading to the snowfields is the only new condition on intrastate travel.
Mr Merlino would not rule out the additional measure remaining in place beyond June 25, when restrictions are likely to ease again for Melbourne and regional Victoria.
Australian Associated Press