A spike in coronavirus cases in Victoria should serve as a wake-up call to all Australians not to become complacent about the risks the disease still poses.
Victoria has stepped back plans to ease restrictions as of Monday to clamp down on several clusters of new cases.
The outbreak has been used by Western Australia as justification for not naming a date to reopen its domestic borders.
Victoria recorded 16 new cases on Monday, its sixth straight day of double-digit growth.
Health authorities have put the outbreaks down to extended family gatherings, with most of the new cases mild versions in young people.
Australia's chief medical officer was confident the southern state's authorities could get things under control.
"If this outbreak escalated and we had several hundred cases, that would be the sort of situation where I would be extremely concerned," Brendan Murphy told reporters in Canberra.
"But they are throwing every resource at this ... and responding in a way that I have every confidence they are doing everything they can to bring these outbreaks under control."
Despite this, WA Premier Mark McGowan described the situation in Victoria as dire.
He outlined a plan to return his state to effectively pre-virus conditions by July 18, including allowing sports stadiums to have full-capacity crowds and halving physical distancing requirements.
However, he said he had intended to announce a tentative plan to reopen the state's borders on August 8 but because of the spike in cases in Victoria now would not nominate any date.
"Right now, it would be irresponsible of me to earmark that date as our potential opening with the rest of the country," Mr McGowan said.
Prime Minister Scott Morrison says the new cases shouldn't come as a surprise.
"COVID hasn't gone anywhere. It's still out there and it can still take hold. And so we can't be complacent about it," he told reporters in Sydney.
NSW Premier Gladys Berejiklian bluntly warned people not to travel to or from the hotspots.
"Don't assume that it won't happen in New South Wales or anywhere else," she told reporters.
"It can happen very quickly, just with a couple of cases, a couple of incidents of people spreading the virus unintentionally can cause a spike.
"It's a good wake-up call for all of us."
ACT's health minister, Rachel Stephen-Smith also cautioned against complacency, saying she was disappointed at the number of businesses not enforcing distancing requirements while Canberrans enjoyed a further easing of restrictions over the weekend.
Inspectors had forced several bars to turn people out after they exceeded the number of people allowed for their floor space, had allowed people to drink while standing or had unsafe queuing, she said on Monday.
There have been 7479 virus cases confirmed across Australia, with around 460 active cases. The death toll remains at 102, relatively low by international standards.
Australian Associated Press