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Adelaide COVID Cluster Casts Doubt On Border Openings

A coronavirus cluster in Adelaide has grown to 17 cases, casting fresh doubts over all states and territories opening their borders by Christmas.

Federal Health Minister Greg Hunt is confident South Australian authorities will bring the outbreak under control.

He has offered to send Australian Defence Force troops, and a national incident centre is being set up.

"If more is required, more will be provided," Mr Hunt told the ABC on Monday.

"But these are the sorts of challenges that if we trade or engage with the world, if we bring Australians home, we will face, in a world where there's over half a million cases a day.

"Having these strong testing, tracing and isolation systems are absolutely critical and South Australia - on all the evidence - does have exactly that."

Federal Minister for Health Greg Hunt. Image: AAP.

The cluster has already caused major disruptions, with Western Australia making a snap decision to reimpose border restrictions.

The Northern Territory and Tasmania have also declared South Australia a coronavirus hot spot, triggering strict quarantine requirements, with other states expected to follow suit.

Prime Minister Scott Morrison said the Adelaide outbreak was a reminder to all Australians.

"Even after a lockdown, even after all of this time, the virus hasn't gone anywhere and it can be activated," he told 3AW radio.

"That's why none of us can be off our game, you've got to stay match fit on this all the time."

Victoria has now gone 17 days without any coronavirus cases or deaths.

But Mr Hunt, who hails from Victoria, is reluctant to give the state government credit for keeping the state in lockdown while bringing a second wave under control.

WATCH: The City of Melbourne has created a 'digital time capsule' so future generations can understand what life was like in 2020.

"We always supported, reluctantly and regretfully, going into lockdown once the contact tracing system wasn't able to cope in Victoria," he said.

"There were some differences about the speed at the end, particularly once they were well below their case level that NSW was able to manage.

"We felt that perhaps we had more confidence in their system than they did on the way out."

He and Mr Morrison are visiting Victoria to announce a new, hi-tech vaccine manufacturing facility being developed in Melbourne.

The government has struck a $1 billion deal with Seqirus, a subsidiary of CSL, to rapidly manufacture vaccines in response to future health pandemics.

The pair will also meet Victorian Premier Daniel Andrews and are likely to discuss reopening the Melbourne Airport for people returning from overseas.