Dr Young said the lockdown was needed to immediately and quickly manage the potential spread of the highly contagious United Kingdom variant.
The woman also had the United Kingdom mutant strain of COVID-19 and had been in quarantine in Melbourne for 10 days before being allowed to fly but has since tested positive for the virus.
The infected cleaner, a Brisbane woman in her 20s, had been working at the Hotel Grand Chancellor at Spring Hill which housed patients with the strain.
The case was the husband of a cleaner who contracted the virus from hotel quarantine, sparking a three-day lockdown in Greater Brisbane which ended 6pm Monday.
Ms Courtney said people who arrived in the 24 hours after the high-risk declaration was made won't have to pay for their quarantine costs. "I think that will become the norm".
"The average incubation period is five days, and mostly it can go out to 12 or even 14 days".
Health authorities will remain on heightened alert during the 14-day virus incubation period and restrictions will remain in place in Greater Brisbane until at least January 22.
There are now 20 active cases in the state, while 19,000 tests were undertaken in the last 24 hours following the positive result to UK's highly contagious strain which came from a woman who worked as a cleaner at Brisbane's Hotel Grand Chancellor quarantine hotel.
Opposition Leader David Crisafulli said the lockdown created uncertainty for business but it was a relief to see there were no new virus cases.
He visited the Acacia Ridge Bunnings store between 2pm and 2.40pm and Sunnybank Cellars in Sunnybank Hills on January 6 between 2.05pm and 2.15pm.
There were a further two cases confirmed in hotel quarantine.
Further tests are underway to determine if these three cases have the United Kingdom strain of the virus. Anyone with the mildest of symptoms, such as a scratchy throat or runny nose, should get tested immediately, NSW Health says.
Dr Young said she thought South Australia had "brilliantly" handled an outbreak in Parafield last November, which temporarily sent the state into the nation's strictest lockdown.
"It is for 10 days only and then hopefully if we get zero community transmission over those 10 days then we can just go back to the rest of Queensland", Palaszczuk said.
"We wouldn't be surprised if there were additional cases than the ones that we have identified, because it is highly contagious", she told Channel Nine's Today show.
The UK strain is among several emerging variants around the world believed to be more infectious than those which have spread previously.
"If you look at Adelaide where they had a short lockdown, it really didn't make any difference", he said.
As case numbers drop, Sydney's Northern Beaches are coming out of lockdown today, but will still be subject to the restrictions applying for the rest of Sydney.
