Mr Morrison says considering Australia's response to the twin crises sparked by COVID-19, it has performed better than almost every other country.

"We are in an extraordinary time. None of us could have imagined what 2020 would have become," the PM told the South Australian Liberal Party annual meeting in Adelaide on Saturday.

"It has been a hard and a tough year like few we have ever known."

The PM said the global economy would fall by six per cent this year and in the June quarter the Australian economy fell by seven per cent.

He said having put in place strong health disciplines to suppress the virus, Australia's focus must also be on "getting the jobs back, getting the businesses open again".

"We cannot allow the virus to tell us how to live," he said.

"We have to live with the virus. You can't pretend it's not there.

"We are dealing with a set of conditions which mean you can't do government as usual. You can't do politics as usual.

"You have to have an unprecedented response and you have to stay very focused on what you're trying to achieve."

The meeting was held under COVID-19 restrictions with seats spaced 1.5 metres apart, though long lines to enter showed less strict compliance with social distancing.

Mr Morrison was only able to go to Adelaide after the state government eased COVID-19 border restrictions on Thursday, dropping the two-week quarantine requirement.

The PM said he had been "busting" to come to Adelaide and expected thousands of Sydneysiders to "be right behind me", providing an $800 million boost to the state's economy.

South Australian Premier Steven Marshall told the meeting Adelaide was currently the safest city in the safest country and had led the nation in its response to the pandemic.

He said the state had also arrested the "brain drain" of young people and skilled professionals leaving SA for opportunities elsewhere.

The premier said latest figures to the end of March, which did not factor in the impact of the coronavirus, showed total migration from SA amounted to just more than 200 people, a significant turnaround.

"There's much more work to be done but let's continue to work together," he said.

Australian Associated Press