Another eight coronavirus cases have emerged in Brisbane with two clusters now totalling 15 cases.
Premier Annastacia Palszczuk says six cases are believed to be linked to existing cases, while two are still under investigation.
She says there are now two distinct clusters of the UK variant of COVID-19 in Greater Brisbane, which has been locked down for three-days to stem the spread.
"Now of course we want to get on top of this community transmission," the premier said.
"So the steps that we took to go into this lockdown, as you can see by those numbers of community transmission today, was absolutely the right call."
Both clusters are linked to frontline healthcare workers who worked at the Princess Alexandra Hospital when they were not vaccinated.
The first cluster is linked to a PA Hospital doctor who tested positive on March 12.
The cases linked to the doctor include two men in northern Brisbane, the brother of one of the men and two colleagues of the other man.
The second cluster is centred on a nurse at the PA hospital and her sister.
One person linked to the pair, and another five people who attended a party with them in Byron Bay, also tested positive in Brisbane and the Gold Coast overnight.
Dr Young said there's also another two cases, which are believed to linked to the two clusters, but testing is underway.
"So we understand all of those movements, but we've had a lot of people now out in the community, infectious, so that's why we need this three-day lockdown to get on top of all of the contacts of all of these positive cases and work out where they have been," Dr Young said.
"Having everyone in their home instead of out and about in the community just helps us get on top of all of the contacts and minimise the risk of further spread."
There are now more than 60 potential virus exposure sites across Greater Brisbane.
Dr Young said she would mandate that anyone working with COVID-19 patients has to have had their first vaccine dose.
More than 41,000 frontline workers have received their first jab already, but only about 7000 are fully vaccinated.
Health Minister Yvette D'Ath said a mandate could not be brought in earlier because they had not reached a "critical mass" of first doses administered.
"To say we could have done that one, two weeks ago, that would have meant we're putting our staff at risk, and the patients we're managing, because we wouldn't have had enough staff vaccinated by that time," she said.
About 2.5 million people in Greater Brisbane into a snap three-day lockdown on Monday afternoon.
Hundreds more people around the state who have visited Brisbane since March 20 are also under orders to stay at home and self-isolate.
The premier said it was too early to say if the lockdown would end on Thursday afternoon.
"We just have to take this day by day, I said that we will give you the most up to date information we can every single morning, and so far the fact that we have these cases that are linked is good news, that is good news," Ms Palaszczuk said.
"Do we expect to see more cases - probably, probably we will see more.
"The big question will be whether or not we see unlinked community transmission."
- Australian Associated Press
