Western Australia is likely to keep quarantine restrictions in place for Victorian travellers even if the state's streak of no new cases continues.
Premier Mark McGowan says an "ultra cautious" approach is necessary after South Australia plunged into lockdown to contain a COVID-19 cluster.
WA recorded six new cases on Wednesday, all returned overseas travellers in hotel quarantine.
Victoria, having emerged from its own lengthy lockdown, meanwhile posted its 19th straight day of no new cases or deaths.
Under WA's new controlled border regime, travellers from Victoria and NSW are still forced to quarantine for two weeks upon arriving. Those states must go 28 days with no new cases before the requirement is removed.
Mr McGowan said health authorities would weigh up how to proceed as Victoria drew closer to the 28-day threshold.
"Obviously what has happened in South Australia means we are ultra cautious," the premier told reporters.
"Victorians and NSW people have to quarantine for two weeks and be tested. Changing that regime, we'll get further medical advice but what's happened in South Australia makes me more determined than ever to be cautious."
Travellers from Queensland, Tasmania and the territories are not required to quarantine.
With no community spread of the virus in more than seven months, WA's COVID-19 testing numbers have dwindled.
Mr McGowan said WA had a "huge amount" of testing kits and other resources ready in the event of an outbreak.
But amid continued tension between the states and the Commonwealth, Mr McGowan said border controls remained the most effective weapon.
"My view is the best thing to do is keep the virus out," he said.
"The model by which you have outbreaks and then contact trace and crack down on it is not the best model.
"That seems to be the NSW model. It is not the best model. Our model whereby you keep it out is the better model and we are determined to continue down that track."
WA on Monday closed its border to SA, denying entry to anyone from that state who does not meet limited exemption criteria.
Mr McGowan said 87 passengers had arrived on a flight from Adelaide on Tuesday. Two people were turned back and the rest, overwhelmingly West Australians returning on compassionate grounds, were admitted to quarantine.
Australian Associated Press
