Queensland has recorded two locally acquired coronavirus cases - news the state's Premier Annastacia Palaszczuk has described as "very, very encouraging".
One of the new cases found on Wednesday is a close contact of an existing case and was already in quarantine.
The second is a 37-year-old woman who works at the Qatar Airways check-in counter at the Brisbane international airport, who has been to limited places around her local area.
Two more overseas cases were detected in hotel quarantine.
Ms Palaszczuk said it was encouraging news for Queenslanders hoping lockdown will end at 6pm on Friday but they were not "out of the woods" yet.
"We've still got another 24 hours to go to see what happens ... and we'll update you tomorrow in relation to whether or not we can leave that lockdown," she told reporters on Thursday morning.
"But like I said, it is very very encouraging for us at this stage."
Millions of people in southeast Queensland, Townsville, Magnetic Island and Palm Island are in lockdown amid four separate virus outbreaks, including three involving the more contagious Delta variant.
Chief Health Officer Jeannette Young said the Qatar Airways worker likely contracted the virus at the airport, where she was checking in passengers while being exposed to flight crew members.
"We don't always know which of them are positive, which is why I really and truly insist people must wear masks at the international airport, and our domestic airports, that is really critical," she said.
Meanwhile, Health Minister Yvette D'Ath has appointed a private doctor to lead a probe into why a 19-year-old clerical worker, who caught the Delta variant while working outside a COVID-19 ward, wasn't vaccinated.
Mater Health Infectious Diseases Physician Paul Griffin will look into what happened at the Prince Charles Hospital, she says.
Dr Young on Thursday , but wait for Pfizer, due to the extremely low risk of an extraordinarily rare blood clotting disorder.
"I have put my advice out there very, very clearly. Now, people need to work out where they want to get advice from," she said.
Additional reporting by Tom Stayner.
