The gradual reopening of other state borders is making it harder to justify following suit in Western Australia, the state's chief health officer says.
Having gone almost six months without any community spread of COVID-19, WA has refused to set a date for welcoming back interstate travellers.
It has also rejected travel bubbles with states such as South Australia that have similarly eradicated community transmission.
Chief Health Officer Andy Robertson is concerned the virus will spread as people from higher-risk states are allowed to travel.
In recent weeks, SA has opened its border to NSW, Queensland has promised to follow suit and the Northern Territory has outlined plans to allow visitors from regional Victoria.
"If we reopen our borders up to other states, we then rely on their borders," Dr Robertson told ABC radio on Tuesday.
"We're not concerned specifically about states likes South Australia and the Northern Territory. But people can do that sort of border-hopping and rapidly travel in."
NSW has now gone 11 days without community spread but Victoria continues to grapple with unknown source cases.
The other complicating factor is the lack of restrictions on physical distancing or large gatherings within WA.
"Because we have opened up our society - people can socialise and go to work and enjoy themselves - we are actually quite susceptible to a case," Dr Robertson said.
"If we get even one or two cases coming in, we're likely to get a serious outbreak which may require further restrictions."
Authorities were reviewing restrictions to see what relief could be found, he added.
But it was unlikely WA would reintroduce some restrictions to allow state borders to reopen.
"That is a possibility but I think we're at a stage now where that would have a serious impact on people's work ... on people's ability to get out and about," he said.
"And I think the benefits for people in WA would be outweighed by those restrictions."
WA's borders have been closed to anyone except designated workers and people exempted on compassionate grounds since April.
Premier Mark McGowan last week faced criticism for appearing to reject a travel bubble with SA and the NT on economic grounds.
"There is no benefit," he said.
"The other states want us to open the border so that West Australian tourists will flood east, not so that people from the east will come here."
The comments frustrated industry groups and the federal government, who have called on Mr McGowan to provide certainty on the border situation.
WA recorded no new cases on Tuesday. There are 14 active cases, most linked to an outbreak on a bulk carrier off the Port Hedland coast.