An emergency department nurse has tested positive for COVID-19, as Victoria records 41 new cases and targets community transmission.
The Royal Melbourne Hospital confirmed the diagnosis on Saturday, saying all the woman's known contacts had been informed and were receiving support.
It is not yet known whether the nurse went to work at the Parkville hospital while infectious.
Eight of the 41 latest cases are linked to known outbreaks, one is a returned traveller, 13 are from routine testing and 19 are being investigated.
"This is not something any of us have experienced before," Deputy Chief Health Officer Annaliese van Diemen said on Saturday as the state recorded an 11th consecutive day of double-digit rises.
"We know that cases and outbreaks will continue to occur, and we really are doing our best to keep absolutely on top of them."
Dr van Diemen said 15 of the new cases under investigation were the result of community transmission with "no clear source".
The state has 204 active cases, with five in hospital, including one in intensive care.
Emergency text messages are being sent to residents in Keilor Downs and Broadmeadows, where there is a large proportion of fresh cases, urging them to get tested.
They are being told there are testing vans, door-knockers and expanded community engagement teams in their area.
Of the eight new cases linked to known outbreaks, all but one are existing close contacts of known cases at Wollert, North Melbourne, Albanvale Primary School and Stamford Plaza.
Dr van Diemen said tests that return a very low positive or are undetermined are being re-analysed.
Victoria is seeking legal advice on whether testing for returned travellers can be mandated following the revelation that 30 per cent are refusing to be tested.
Dr van Diemen sought to allay concerns about the 30 per cent refusal rate, saying that figure related to overall numbers since hotel quarantine began and that recent refusal rates were lower.
She also said there was no evidence of community transmission being linked to people leaving hotel quarantine and that it was not ideal to compel travellers to stay longer.
The situation differs to NSW where returned international travellers who refuse to have the test on day 10 must stay an extra 10 days in quarantine.
NSW has a two per cent test refusal rate, authorities have confirmed.
Treasurer Josh Frydenberg said on Saturday it was important to test and trace, otherwise lives would be endangered.
Victorian Opposition Leader Michael O'Brien said it made no sense that people could refuse the test, and if so, should pay for their stay.
Victoria has ramped up testing with a focus on 10 suburbs with high community transmission: Keilor Downs, Broadmeadows, Maidstone, Albanvale, Sunshine West, Hallam, Brunswick West, Fawkner, Reservoir and Pakenham.
More than 758,000 total tests had been done to date on Saturday, an increase of close to 22,000 in the past 24 hours.
The total number of recorded cases is now 1987, with 1762 recoveries, and the death toll remains at 20.
Some of the 200 specialist medical and support personnel from the Australian Defence Force are understood to have arrived in Victoria to help in the state's efforts.
Meanwhile, almost 5000 thermometers are being shipped to Victorian vacation spots as the school holidays begin.
Australian Associated Press