SA COVID-19 outbreak 'good lesson for all of Australia'

South Australia's coronavirus outbreak is a "good lesson for all of Australia", Deputy Chief Medical Officer Professor Michael Kidd says.

This comes as the state reported one new case overnight, taking the cluster in Adelaide's north to 18.

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"We are still in the grip of the global pandemic and COVID-19 is raging out of control very sadly in many countries around the world and we need to be prepared," Professor Kidd told Today this morning.

"We expected we were going to get further outbreaks as we continued to have people coming into Australia, both returning travellers but also those importing and exporting our goods for us."

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Huge lines are forming at testing stations across the city this morning, with some wait times blowing out to 11 hours.

South Australians have been congratulated for their response.

"We've seen a very swift and rapid response with the testing, contact tracing, isolating and the public doing their part as well," Professor Kidd said.

"Most importantly, the people of Adelaide doing as they should and lining up to get tested. Congratulations to everybody."

He said despite this "very worrying time" for all Australians, he is not concerned about large crowds at tomorrow night's State of Origin decider in Brisbane.

Suncorp Stadium will be at full capacity as Queensland begins easing COVID-19 restrictions.

"One of the things that we know about the stadiums and the sporting events is that they are controlled and they are being carried out in a COVID-Safe way," he said.

"So I'm confident that the authorities will be putting their COVID-Safe plan in place and making sure that that event is as safe as possible for the people taking part."