Queensland has recorded its first community COVID-19 transmission in two months after a pair of "reckless" teenagers allegedly lied when they crossed the border from NSW and infected a contact.
The two 19-year-old women tested positive on Tuesday after flying in from Melbourne via Sydney and their contact, who works in childcare, was diagnosed with the coronavirus on Wednesday.
Visitors from Sydney will now be banned from entering Queensland after premier Annastacia Paluszczuk declared the entire city a COVID hotspot.
Police are investigating the two women for allegedly falsifying their border declaration passes when they arrived at Brisbane Airport from Melbourne, via a brief stopover in Sydney, on July 21.
They tested positive eight days later, sending parts of Brisbane into lockdown.
Queensland Chief Health Officer Dr Jeannette Young called the 19-year-olds "reckless" and said contact tracing was underway.
"While we are still determining where the virus may have been acquired, we are working closely with these women to gather necessary information, including other places they may have visited whilst infectious," she said.
The teens attended a medical practice and five restaurants and bars including two at Southbank. They visited six different suburbs including South Brisbane, Woodridge, Browns Plains and Sunnybank.
Shopping centres, restaurants, a school and a church have been closed.
Their 22-year-old contact works at YMCA Chatswood Hills Outside School Hours Care.
Ms Palaszczuk is seething over the alleged breach and the potential for community outbreaks.
"I'm absolutely furious this has happened," she told reporters on Wednesday.
"We do not want a second wave here. We do not want widespread community transmission.
"They have given to authorities misleading information."
Queensland residents returning within 14 days of visiting Melbourne, or other declared hotspots, are required to go into hotel quarantine at their own expense.
Queensland will ban Sydney visitors from 1am on Saturday, having blacklisted all of Victoria earlier this month after case numbers escalated in the southern state.
NSW Premier Gladys Berejiklian was blindsided by the announcement which came after an outbreak in the city's inner east.
"It would have been nice if she told me, but that's fine," she told reporters.
The teens, from Acacia Ridge and Logan, are being treated in the Princess Alexandra Hospital.
Anyone providing false, misleading or incorrect information on a Queensland Border Declaration faces a fine of $4004, or a court-imposed penalty of up to $13,345 and jail.
Scores of their friends will be forced to isolate as authorities scramble to conduct contact tracing.
A fever clinic will be set up at the college to test students, staff and community members.
Queensland now has eight active cases of coronavirus.
Australian Associated Press