Victoria's response to the spread of coronavirus will be overseen by its state control centre, as another three people were confirmed as having the illness.
Premier Daniel Andrews said the authority will coordinate government agencies grappling with the virus outbreak, which has been categorised as a "class two" emergency.
Class one emergencies include natural disasters such as bushfires and floods, while class two emergencies include extreme heat and energy issues.
"The central coordination of our response is very important. We've learnt that many different times in different circumstances," Mr Andrews told reporters in Melbourne on Wednesday.
Emergency Management Commissioner Andrew Crisp said the control centre will collate intelligence on exactly how the issue is unfolding.
"Good information will lead to good decision making," he said.
Another three Victorians tested positive for COVID-19 overnight after flying back from the United States, bringing the state total to 21.
Victorian Premier Daniel Andrews. Source: AAP
Among them is a man in his 50s who became unwell upon his return to Melbourne from Seattle on Saturday, on Virgin flight VA24.
He is recovering in home isolation, and three close contacts - including two children - are also in quarantine.
Before being diagnosed, the man visited the Mussel and Jazz Festival at South Melbourne Market on March 7 between 2pm and 3.30 pm, then went to the Rebels and Lions rugby match at AAMI Park where he sat in section 9.
The other two cases had been on flights which have had confirmed COVID-19 cases this week - UA0600 and QF94 - but are understood to have contracted the virus while in the United States.
One of them, a man in his 50s who returned from Los Angeles on Friday, is a staff member at Yeshivah and Beth Rivkah Colleges at St Kilda East.
He worked for half a day while infectious on Monday and the school has closed for 24 hours.
The other new case is a woman in her 20s who travelled through the United States and became unwell on February 29, after returning to Melbourne on the same day.
She is also recovering in home isolation.
More than 1000 Victorians went to seven clinics set up in hospitals across Melbourne on Tuesday to be tested for the virus.
Health authorities are expected to set up 100 "pop up" coronavirus clinics across Australia, as part of a $2.4 billion response package.
Health Minister Jenny Mikakos expects some of them may well follow the approach taken by a GP in Melbourne's western suburbs, who has been performing "drive-through" tests in his clinic car park.
Meanwhile, the federal government has imposed a travel ban on Italians arriving in Australia from 6pm on Wednesday, adding to existing bans on residents of China, Iran and South Korea.
