Queensland has recorded eight new locally acquired cases of COVID-19, with two confirmed clusters now in the state.
Premier Annastacia Palaszczuk said six of the new cases are close contacts of known infections, with another two under investigation.
There were two overseas-acquired cases, both from Papua New Guinea. There are now 78 active cases in Queensland hospitals.
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"We now believe that there are two distinct clusters," Ms Palaszczuk said.
Chief Health Officer Jeannette Young said it is "good news" the new cases can be linked.
The first cluster is related to a doctor at the Princess Alexandra Hospital who treated a confirmed case, Dr Young said.
The second cluster is linked to a nurse who worked at the same hospital on March 18 in the COVID-19 ward, Dr Young said.
Dr Young said genomic testing links the nurse to a returned traveller from India.
A sister of the nurse is also linked to that cluster, and now five further cases have been added to that outbreak.
The five new cases were part of a hen's party that visited Byron Bay, sparking alerts in the northern NSW holiday town.
New details on tradie who attended Byron Bay party
A man who attended the Byron Bay hen's party as an "entertainer" has tested positive for the UK strain and is part of the second cluster, Dr Young said.
"One of the positive cases in that second cluster attended the hen's party as an entertainer," Dr Young said.
"And he came back and he lives in the Gold Coast and he works as a tradie, and he did go to an aged care facility in the Gold Coast."
Dr Young said residents at the aged care facility had been given their first vaccination dose.
"I haven't got confirmation about whether any have received their second dose," she said.
Queensland health authorities are working with Federal Government to monitor the facility.
Risk of further infections high
Dr Young warned "we have had a lot of people now out in the community infectious".
She said COVID-positive people in the clusters had visited places outside Brisbane, so the risk of spread further afield is high.
"We know we have had infectious people in the community," she said.
All people in both clusters are currently in Queensland, Dr Young confirmed.
Two clusters 'very different'
Dr Young said both clusters spreading in Queensland are the UK strain of the coronavirus, but they are "very, very different".
The first cluster linked to the doctor at Princess Alexandra Hospital has had an additional five cases linked to it, in addition to the three known yesterday.
The second cluster linked to the nurse has seven known cases, not including the returned traveller.
Dr Young said there is one more case that her team is now trying to work out which cluster it is linked to.
An investigation has been launched into how the doctor and nurse became infected.
New cases come on first full day of lockdown
There were 14,589 tests in the last 24 hours in Queensland.
Yesterday, Ms Palaszczuk announced a three-day greater Brisbane lockdown as a "protective measure" to avoid a longer shutdown.
It came after four new locally acquired cases were announced.
Vaccine rollout 'ramping up'
Queensland Health Minister Yvette D'Ath confirmed 65,129 vaccine doses have been administered in the state.
Last week, 20,000 doses were given, Ms D'Ath said, adding the rollout was "ramping up very quickly now".
Ms D'Ath said hospitals in Queensland were now being advised to only let health workers who had been vaccinated to work with frontline patients.
"The reality is that we have a large number of positive cases in our hospitals now," Ms D'Ath said.
Toowoomba visitors went to hotspot pub
Dr Young said she was mildly concerned about a group of travellers from Toowoomba who visited a hotspot pub in Brisbane.
"We've not had any positive cases amongst that group, but they were at one of the venues of concern," she said.
Toowoomba, Hervey Bay, Gladstone and the Gold Coast in Queensland, and Byron Bay in NSW, are potential outbreak risks because of people travelling, Dr Young said.
