Brisbane's community COVID-19 outbreak has grown by another eight cases, Queensland Premier Annastacia Palaszczuk has announced.
The Australian city entered a three-day lockdown on Monday after a community cluster grew and two other cases emerged without explanation.
Six of the infections announced on Tuesday have been linked to previous cases and another two are under investigation. Two others are linked to overseas travel, and were detected at the border.
"The good news is that these cases are linked, and we now believe that there are two distinct clusters," Palaszczuk said at a press conference on Tuesday morning (local time).
Queensland's chief health officer Dr Jeannette Young added that all the community cases investigated so far have been linked to clusters, so "we don't have community transmission out there we're not aware of".
She says the two cases currently under investigation are likely linked to a doctor at Princess Alexandra (PA) Hospital. He's been identified as the source of the first cluster, she explained, which is currently made up of eight confirmed cases.
"I’m very grateful to that first young man who came forward and got tested, and the second gentleman - so, they live in northern Brisbane - those two cases, and we've had other cases connected to those.
"We know they’re all linked because of the genome sequence. They’re all a B117 linked back to that case at the PA Hospital."
The second cluster - now made up of eight people, with potential for another once an investigation has been carried out - has been linked back to a nurse at PA Hospital who had been working in the facility's COVID-19 ward earlier this month.
"She has exactly the same genome... to a gentleman who arrived and was treated in the PA Hospital and was tested on 22 March," Dr Young said.
"After the nurse worked in the COVID ward, she did do a shift on the night of 23 March - that shift started 10pm that night, she worked through the night into the next day on the 24th.
"So my hypothesis... is that she has acquired the infection when at work that night."
Dr Young says from Wednesday onward, only people who have had their first dose of a COVID-19 vaccine will be allowed to work directly with confirmed coronavirus cases.