The Northern Territory has recorded two new positive cases of COVID-19 as the list of concerning exposure sites grows.
Authorities are concentrating on isolating all gymgoers who attended a specific Zumba class where a positive coronavirus case was present.
Anyone who attended the Zumba class at the REX Centre in Palmerston on Sunday morning between 9am and 9.30am is now under a stay-at-home order and required to isolate for 14 days, regardless of their test results.
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"We had QR code information from this event. We think about 25 people were there," Chief Minister Michael Gunner said.
"They're all being contacted to isolate. Their household contacts are also under a stay at home order."
Contact tracers have put in a "superhuman effort" to find all 171 patrons who visited The Buff Club in Darwin, where it is believed a super-spreader event may have occurred.
"Remember, all of these people are high-risk close contacts, but they also been in lockdown like the rest of us on Sunday afternoon," Mr Gunner said.
"Our health advice is that the positive case that spent time at the club was probably at his most infectious after the lockdown had commenced."
NT health authorities are worried about the potential for further COVID-19 seeding at a Zumba class due to the nature of indoor exercise.
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Chief Health Officer Dr Hugh Heggie said the evidence showed that hard exercise in a confined space could increase the risk of transmission.
"Why would the Zumba class be rated as higher risk? Because there is evidence that breathing hard, exhaling hard, shouting or singing, increases the risk of spread," Dr Heggie said.
"The purpose of this lockdown is actually to stop the spread in Darwin, and the regions."
The two new cases reported today are the wife and daughter of a previous positive case announced on Sunday.
Both cases live in the Palmerston area and have been in isolation.
The total number of cases linked to the Tanami Desert outbreak is now at nine.
The NT has also declared the Perth and Peel regions in Western Australia and several Local Government Areas (LGAs) in south-east Queensland hotspots.
Mr Gunner said cases were likely to climb throughout the week.
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"I do want to warn people that we are expecting more positive cases throughout this week," he said.
"What gives us hope is how effective the quick lockdown has been, it has meant that the community was largely protected during the infectious period.
"We are still very nervous. We're not close to relaxing yet. There is still a lot worry about.
"But a lockdown is working, I thank everyone in the Top End for what you've done so far to make the lockdown to work.
"Let's keep going."
