Australia's top medical adviser says work is well advanced on how international travel could be gradually reopened but warns it will probably be one of the last things to change.
Tourism bosses and business leaders are eager for Australia to find ways to restart international travel to boost the economy and create jobs.
Chief Medical Officer Paul Kelly says the travel bubble with New Zealand has proven international travel can be done safely but the situation is being carefully monitored before other "green zones" are declared.
"We have a very detailed country risk assessment which we've been asked to do," he told reporters in Canberra.
"Every week I reassess (the New Zealand model) ... that's been very successful.
"We have had many tens of thousands of people who have come across the ditch in the last few months - not a single (positive coronavirus) case.
"That's a very strong indication of that approach and we have done similar country risk assessments in a very detailed way for many of the Pacific islands."
He said despite no other suitable country yet being found for a travel bubble "there are some that are very low risk and that is playing into discussions about how people from some of those countries should be quarantined to make sure it is safe".
"We are definitely open to other bubbles."
However he warned international border changes are unfortunately "probably going to be one of the last things to change rather than the first".
As the first vaccine, produced by Pfizer, moves closer to approval for use in Australia, Prof Kelly said work was also being done on alternatives to hotel quarantine, which would be presented to national cabinet in February.
Queensland will take to this Friday's meeting a proposal to use a mining camp for quarantine.
Prime Minister Scott Morrison is open to the idea.
"I haven't seen that proposal as yet but I've always been very interested in positive proposals that have come forward from premiers about how we can best manage what are very challenging issues," he said on Tuesday.
The prime minister noted there were similar arrangements at the Northern Territory's Howard Springs camp which the federal government helps run.
The facility near Darwin will shoulder much of the quarantine workload created by an extra 20 flights to bring stranded Australians home.
There were no cases of local coronavirus transmission in Australia on Tuesday, the fourth day in the past five that has been the case.
Victoria recorded four new cases in hotel quarantine, three believed to be linked to the Australian Open tennis tournament.
More than 70 players have been forced into hard lockdown in hotels, meaning they can't train for two weeks.
NSW Premier Gladys Berejiklian is urging more people to get tested with the current rate below authorities' target to confidently lift restrictions.
Restrictions are on track to ease in Brisbane on Friday after another day without local transmission.
Victoria has reopened to 16 local government areas in Sydney, while the ACT will drop quarantine requirements for people who have travelled to the northern beaches.
Sydney-based federal MPs in areas still under travel restrictions will also be able to apply for an exemption to enter Canberra for parliament.
Australian Associated Press