A man with COVID-19 who presented a Perth hospital emergency department has forced some of its staff into isolation.
The vaccinated man in his 60s turned up at Fiona Stanley Hospital with non-respiratory symptoms, Health Minister Amber-Jade Sanderson said on Wednesday.
About 12 emergency department workers have been identified as close contacts.
Police believe the man is linked to a cluster of Omicron cases across several Perth massage parlours.
"The contact tracers are working hard to get information from this gentleman. I don't think it's been straightforward," Ms Sanderson told reporters on Wednesday.
"(Police) use a range of techniques, CCTV and investigative techniques, to establish people's stories versus what is actually the case. But we also had information from a third party."
The man, who has been placed in hotel quarantine, lives with four other men who will also enter quarantine and have been tested.
Ms Sanderson said the hospital staff had been wearing personal protective equipment.
With the WA government still yet to update close contact definitions ahead of the February 5 border reopening, the staff members could face up to a fortnight in quarantine.
"The protocol is 14 days because they're deemed a close contact. That was the immediate response from the health team to put them in," she said.
"But they'll work through the exact nature of their contact to determine whether they're able to come back sooner than that upon negative testing.
"We've seen that, certainly in hospitals around the country, 14 days' isolation for close contacts is not sustainable for the health system."
The Australian Medical Association and Australian Nursing Federation have urged the government to immediately release more information about the reopening plan, including modelling on the impact of the Omicron variant.
But Ms Sanderson suggested it would be premature to base decisions on modelling before the borders reopened, despite other states having done so.
"Omicron has only been in the community since the end of November. That is not enough time to get a full dataset to get a clear picture," she said.
"I think it has to play a role but there will be a range of other factors that we have to take into consideration."
The minister said close contact definitions and hospital surge plans would be communicated to healthcare workers in coming days.
WA Liberal leader David Honey said with just over a fortnight until borders reopen, businesses had no clarity on staff infection protocols.
"The premier needs to stand up and give a guarantee to the people of Western Australia, that this state is ready for the opening date that he chose," he told reporters.
A second local case reported on Wednesday involves an unvaccinated man in his 50s who has also been linked to the cluster.
He has been in quarantine during his infectious period.
The state now has 34 active Omicron cases with double-dose vaccination nearing 90 per cent.
