A flight attendant infected with COVID-19 during hotel quarantine has spread the virus to a man at a Brisbane venue attended by more than 30 other people.
Queensland authorities believe the risk posed by its latest case of community transmission is low.
The man was at the Portuguese Family Centre at Ellen Grove in Brisbane on Saturday night at the same time as the infected flight attendant.
He and 35 others who were also at the venue are now isolating as authorities wait on further tests to see if anyone else is infected.
Authorities believe the flight attendant contracted the virus while in hotel quarantine. She was released on Saturday, before a test showed she was infected.
She was only in the community for a short period but has sparked alerts for a number of exposure sites including the Portuguese centre, the DFO Brisbane shopping centre, the lobby of the Park Regis Hotel, and an area near the Queen Street Mall.
Chief Health Officer Jeannette Young expressed optimism that risks from the new infection were low.
Contact tracers are working to determine if he ventured out after going home from the family centre, and being told on Sunday that he was infected.
Dr Young also shed light on how the flight attendant caught the virus.
Preliminary investigations show a worker at the quarantine hotel escorted an infected man, who'd arrived from Mongolia, to an ambulance. The same worker then went to a higher floor and swabbed the flight attendant.
"The lady ... has then ended up with exactly the same virus as the gentleman from Mongolia," Dr Young told reporters on Tuesday.
"So we are thinking - but we really need to do further investigation - that through a transmission process that staff member has transferred the virus from the gentleman."
The man from Mongolia and the quarantine hotel worker were both fully vaccinated, Dr Young said, reinforcing that the virus can be passed on even by those who have had their shots.
Meanwhile, Queenslanders have been told to reconsider travel to NSW after the state recorded 10 new local cases, taking the number of infections linked to Sydney's Bondi cluster to a total of 21.
"People should reconsider their need to go to Greater Sydney," Dr Young said.
"Overnight there's been two new exposure venues in Canberra. People need to look before they travel anywhere in NSW and should reconsider if they really need to travel."
Victoria, on the other hand, was on top of its outbreak, Dr Young said.
As a result, Queensland will open its borders to all of Victoria, including greater Melbourne, at 1am on Friday. Victorians must still complete a travel declaration but will not be required to hotel quarantine.
Premier Annastacia Palaszczuk has called on the federal government to provide more certainty over the supply of vaccines, echoing concerns raised by other states about running out.
The premier also said the federal government should approve her plan for a regional quarantine centre in Queensland after the case involving the flight attendant in hotel quarantine.
"Our hotels were not meant to be the last line of defence for this type of infectious disease."
Australian Associated Press