Dr Young said she was closely monitoring the situation in the two states.
“I’m urging Queenslanders travelling to these states to reassess their plans – if it is not necessary, then consider staying here,” she said in a statement.
“The next 24 hours are critical for Victoria and the NSW cluster is growing daily.”
Dr Young said Queensland was in a “good position” after declaring greater Sydney a hotspot and did not want to see that “come undone because of complacency”.
Routine testing had also found COVID-19 traces in sewage taken from wastewater treatment plants at Bundamba, west of Brisbane, and Merrimac on the Gold Coast on December 24.
While this could indicate a resident had COVID-19 and had recovered, it could also signal undetected cases among people who lived in or had recently visited the areas, Dr Young said.
She urged anyone with even the mildest symptoms to get tested.
Positive results were found in seven other sites last week, including Victoria Point, Oxley Creek, Goodna, Fairfield, Cairns North, Redcliffe and Nambour.
“With the New South Wales cluster growing and new cases in Victoria, it’s better to be safe than sorry,” Dr Young said.
Health authorities reported three new cases in Queensland on Thursday, detected among travellers in hotel quarantine who had recently returned from South Africa, India and Pakistan.
All three were transferred to hospitals, with genome sequencing under way to determine the strains.
This testing on one man, who recently returned from Ghana, found he was infected with the UK variant, thought to be more contagious than the original strains.
“This detection highlights the importance of our hotel quarantine policy, especially for overseas travellers,” Dr Young said.
“Cases are rising at a rapid rate internationally and new variants like this one would be difficult to contain in the community.”
Another traveller who recently returned to Queensland became the first in Australia to test positive for a South African strain, also thought to be more infectious.
Matt Dennien is a reporter with Brisbane Times.