Queensland authorities are racing to avoid another lockdown after three locally acquired cases of COVID-19 emerged in Brisbane.
Premier Annastacia Palaszczuk says the three cases include a 12-year-old boy who flew into the state from Sydney on 9 July and his father.
A fully vaccinated Brisbane Airport worker has also tested positive, which is a major concern for authorities.
Ms Palaszczuk says a face mask mandate due to end on Friday for 11 local government areas will be extended for another seven days in a bid to avoid a lockdown.
"I am sure everyone is sick and tired of wearing masks, they are uncomfortable, but they are extremely important and if everyone continues doing it, coming forward and getting tested, then hopefully we won't be required to go into a lockdown," she told reporters
"That is the thing that we all absolutely want to avoid."
The mask mandate will be in place until 23 July in Brisbane City, Logan, Moreton Bay, Ipswich, Redlands, Sunshine Coast, Gold Coast, Noosa, Somerset, Lockyer Valley and Scenic Rim.
Chief Health Officer Jeannette Young said the boy had travelled to the US and arrived back in Australia via Sydney Airport on 21 June with his mother.
He quarantined for 14 days there before flying with his mother to Brisbane on Qantas flight 544 on Friday.
The boy is believed to have given his father the virus after arriving home at Newport on Brisbane's Bayside. The mother has tested negative so far but is now in hospital with her son.
Dr Young said it's uncertain whether the boy picked up the virus in hotel quarantine in Sydney or elsewhere.
The father worked at an office on the Sunshine Coast on Wednesday, but Dr Young believes the family have not visited many other venues in the southeast.
Dr Young said the third case in a female airport worker is more concerning because she is fully vaccinated with Pfizer, and worked three night shifts on Monday, Tuesday and Wednesday while infectious.
"I don't know exactly where they work at the airport, we will have to go through all of that and work out where she's been," she said.
The woman, who lives at Tarragindi in Brisbane's south, visited Woolworths Annerley from 10.36am till 11.36am on Monday and Chemist Warehouse in the same suburb from 8.39am to 8.49am on Wednesday.
The chief health officer is waiting for genomic testing to find out what strains of COVID-19 the three cases have contracted, and where they picked up the virus.
"I'll get confirmation later today, but I suspect they are unrelated to all of our other cases, these are new outbreaks," Dr Young said.
Meanwhile, Dr Young has revealed South Korea informed Queensland Health about a person who was potentially infectious in Ipswich and Brisbane last Friday.
A public health alert was issued on Wednesday night for venues at North Ipswich, Inala and at the Brisbane Airport - all for 9 July.
Dr Young said it's uncertain whether the man was actually infectious as he tested positive upon arrival in South Korea.
"We don't know any of that because the gentleman is not here now," she added.
Ms Palaszczuk has urged Queenslanders in Victoria and NSW to consider returning to the state amid outbreaks in both states.
The premier said people planning trips to the southern states should reconsider their need to travel at all.
"I cannot be clearer. We are seeing these little spot fires happening across the nation and we need to make sure we get this under control," she said.
Queensland reported two COVID-19 cases in hotel quarantine on Thursday.
