Queenslanders have been told to brace for a surge in COVID-19 cases as the state grapples with the most serious threat it has faced for a year.
A lockdown affecting millions has been extended by five days to at least 4pm on Sunday, after 13 new cases were added to an escalating cluster in the state's southeast corner.
What began with a single case on Thursday has grown to 31 in five days.
Chief Health Officer Jeannette Young has told Queenslanders she's expecting "a lot of additional cases" due to the links to schools and the fact many infections are in children who are not vaccinated and are more likely to pass on the virus.
All but three of the 13 cases reported on Monday were in kids aged nine and under.
Seven were students from Ironside State School in inner Brisbane, five were household or family contacts of those students, and one was linked to a case associated with a karate academy that trains at the same school.
One of those cases was active in the community for six days while infectious, demonstrating the level of risk.
"I am very worried about those schools," Dr Young said, after students at Ironside and Indooroopilly State High School tested positive, and four other schools were listed as exposure sites, along with other locations at the The University of Queensland's St Lucia campus.
The already long list of sites visited by positive cases continues to grow with more added on Monday, including Rockhampton Airport and the Rookwood weir site after an infected contractor went there for work.
Students from Mt Morgan State School visited the weir and are being prioritised for testing, although Dr Young has said there's no evidence yet of any direct crossover.
Acting Premier Steven Miles said Queensland was in the grip of an outbreak like no other, involving students, teachers, parents, extracurricular activities and public transport.
He said workers simply must, if they can, do their jobs from home and he warned employers not to misrepresent people as essential workers when they were not.
The government has announced support payments of $5000 for small and medium businesses hit by the lockdown, but they've also been warned they'll have to wait two weeks to apply, while online systems are set up.
Gold Coast Mayor Tom Tate is seeking to limit the economic fallout for his residents, asking the government to exclude the tourist strip from the lockdown because "the clusters only are in Brisbane".
Queensland Health has said there are no plans to lift any aspect of the lockdown early.
Dr Young has appealed to every Queenslander regardless of where they live to get tested at the first hint of any symptoms, saying she doesn't yet know where the virus is, nor how the same strain found in two returned travellers was passed to 29 others.
"We need to lock down really, really hard - the hardest we have ever locked down. If you don't need to leave your house, don't."
Two other cases reported on Monday involve crew members of a bulk carrier off the Queensland coast.
Australian Associated Press