West Australians are nervously waiting to learn the full extent of an "amateur" hotel quarantine breach which has plunged most residents into lockdown.
Metropolitan Perth, the Peel region and South West have completed their first night of a five-day lockdown which will run until 6pm on Friday.
All residents must stay at home unless shopping for essentials, attending to medical or healthcare needs, exercising within their neighbourhood or working if unable to do so remotely.
Schools which were due to resume on Monday will remain closed for another week.
It comes after a security guard at the Sheraton Four Points hotel in Perth's CBD contracted what is believed to be the highly contagious UK variant of the virus, then attended more than a dozen venues over several days while infectious.
The man in his 20s is also a rideshare driver but authorities believe he had not worked in that job since January 22 - several days before likely becoming infected.
Australian Medical Association WA president Andrew Miller has labelled the breach predictable, saying the McGowan government had ignored concerns about the hotel regime.
"It's incredibly disappointing that we are still running what we would describe as an amateurish quarantine system," he said.
"These are not quarantine facilities, these are hotels."
Dr Miller has called on WA to invest in dedicated quarantine facilities not used for any other reasons, proper airborne protection including fresh air ventilated through hotels and supply of N95 face masks for all security guards.
He also wants guards to be better paid and banned from taking a second job.
Anyone in the community who has symptoms is being urged to get tested.
Authorities are also pleading with West Australians not to panic-buy after chaotic scenes at supermarkets and pharmacies.
People must wear face masks anytime they leave the house but with many pharmacies sold out on Sunday, the police commissioner has encouraged people to tie a scarf or bandana around their face while going out to buy one.
WA had gone nearly 10 months without a virus case in the community and the breach will determine how far the state's testing and tracing capacity has come.
WA Health has released a list of 15 venues, mostly in Maylands but also including the Perth Convention Centre and a GP practice in Nedlands, that the guard visited between January 25 and January 30.
Anyone who attended those venues must get tested at a COVID-19 clinic and isolate until their results are available.
The man returned a positive test on Saturday night after last working at the hotel on January 27. He first experienced symptoms the following day.
Genomic testing confirming the source of his infection will not be available until Tuesday morning.
His three housemates have tested negative but have been placed into hotel quarantine for 14 days. Any other close contacts will also be required to isolate.
Authorities are investigating the breach but say the guard did not enter a hotel room.
WA Health meanwhile played down concerns about a man who posted on social media about having tested positive while at Fiona Stanley Hospital.
The man travelled to WA from the eastern states where he underwent 14 days quarantine after returning from overseas.
WA Health said he was awaiting test results in hotel quarantine but initial information indicated it was a historic case which was infectious overseas.
All other states have moved to either close borders or restrict travel from WA.
