Victoria has recorded one new locally acquired coronavirus case on Monday as Premier Daniel Andrews warns of further cases on third day of the state's snap five-day lockdown.
The infection takes the state to 21 active cases and is linked to the Holiday Inn cluster at Melbourne Airport, which now stands at 17.
The case, a female, was identified on Sunday and was under investigation, the Department of Health confirmed.
She took multiple tests which gave differing results, with health authorities treating her case as a "weak positive".
She is one of seven cases linked to a family function in Coburg on February 6.
The case worked at three mental health units at Broadmeadows Hospital, Northern Hospital and the Alfred, with 150 primary contacts across the centres isolating.
Premier warns more cases likely out there
Mr Andrews said the last few cases associated with the outbreak justified the lockdown as they were "not in the original net".
"They were not in our scope, if you like," he said.
He said it validated their ongoing assumption that there are "at least a handful of cases out there that we don't know about".
Department of Health testing chief Jeroen Weimar warned Victorians not to dismiss the threat at hand.
"Please do not regard this as just a localised outbreak, this is a significant outbreak," he told reporters.
A further case has been detected in hotel quarantine.
There were 25,144 tests in the previous 24 hours.
Andrews says 'too early' to call lockdown length
On Sunday, Health Minister Martin Foley said he could not comment on whether the lockdown would surpass its initial five-day timeframe.
"It is too early to say whether we have been successful," he said.
An on Monday, Mr Andrews again refused to shed any light on the length of the lockdown.
"It's too early for us to say. These are promising results but the more detective work you do, the more people that come into focus," he said.
“I know every Victorian on Monday morning wants to know whether this is going to finish on Wednesday night... I’m not in a position to be able to confirm that."
Two restaurant owners on Melbourne's famous Lygon Street told ABC News Breakfast on Monday they feared the lockdown would extend beyond the five days.
Cases at gathering sparked by 'very unusual' event
Two new cases reported on Sunday were a three-year-old child and a woman in her 50s from separate households who were at the family function on Sydney Road in Coburg.
The function was attended by 38 people including a worker at the Holiday Inn who had returned a negative test result on February 7.
The venue was not listed as an exposure site until February 12, two days after the hotel quarantine worker eventually tested positive.
Victoria's Chief Health Officer said a review of the worker's negative test on February 7 found it was a "false negative".
"To be a weak positive but to be infectious enough to actually cause infection in other people at an event is very unusual," Professor Sutton said.
The three-year-old child attended Glenroy Central kindergarten and Goodstart Early Learning Centre in Glenroy, with a combined 101 primary contacts identified between the two locations.
There are 1350 primary contacts linked to the Holiday Inn outbreak in total.
Mr Weimar urged anyone in the Coburg and South Melbourne areas to get tested if symptoms arise after “wastewater detections” in the local catchment areas.
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