West Australian authorities are tracing the movements of a person believed to have been infected with the Omicron variant while in the community.
The person, identified as Case 1244, had close contact with a confirmed Omicron case who recently returned from Tasmania.
They subsequently spent several days in the community in Perth, although WA Health said on Tuesday the public health risk appeared to be low.
Three other local cases were reported, including a truck driver who arrived from South Australia and two close contacts of a previous truck driver infection. All are in quarantine.
A number of new exposure sites have been added to the HealthyWA website, including supermarkets and pharmacies in Perth's southern suburbs.
Testing clinics have also had their operating hours extended.
Health Minister Amber-Jade Sanderson said genomic sequencing was expected to confirm Case 1244 had the Omicron strain.
"There's a strong possibility there's been community spread of Omicron," she told reporters.
"This is just part and parcel of managing a really aggressive strain of this virus."
Ms Sanderson said Case 1244 travelled to the airport on January 2 to pick up a family member who had returned from Tasmania.
She said the infected person had worn a face mask at the airport and followed all other rules.
The state government on Tuesday launched its new ServiceWA app, integrating proof of vaccination records, the SafeWA QR system and the G2G travel pass.
It comes as the government prepares to ramp up restrictions for the unvaccinated ahead of the February 5 border reopening.
Details are expected to be confirmed later this week but those who refuse to get vaccinated face being locked out of pubs, restaurants, cafes and gyms.
It's expected there will also be some escalation of restrictions for the vaccinated such as mask-wearing and gathering limits.
Ms Sanderson said the experience of other jurisdictions, particularly NSW, highlighted the need to have both high levels of vaccination and public health measures.
"Having both of those things in place is really important in terms of managing the flow of the virus," she said.
"There will be broad public health social measures to slow, limit and prevent the spread. That will go across the community, whether it's vaccinated or unvaccinated.
"But I would make the point that if you are unvaccinated, there will be significant limits on the things that you can do and what you can engage in."
Police Commissioner Chris Dawson said police would not have access to the app's health data but warned venues would be subject to checks, and on-the-spot fines of $1000 would be issued to those caught trying to game the system.
Almost 94 per cent of West Australians aged 12 and over have received their first dose of a COVID-19 vaccine, while the double-dose vaccination rate is nearing 87 per cent.