Prime Minister Scott Morrison on Wednesday banned inside gatherings of 100 people, hitting pubs, restaurants, movies, shows and other events.

Economist Chris Richardson predicted 180,000 people would lose their jobs by August.

Attorney-General Christian Porter said that would mean people who had never had contact with the welfare system would need it, and the government was looking to change rules to ensure the system was "fair, reasonable and quick".

"Very, very sadly, it's going to mean for a period of time over the next six months that people who have never had any contact whatsoever with the welfare system perhaps for the entirety of their lives, will be needing of assistance from the taxpayer," Mr Porter said on Perth radio.

Mr Richardson predicted a jump in the unemployment rate from 5.3 per cent to 6.7 per cent, with 180,000 people joining the dole queues, a similar number to the global financial crisis, but said a second round of stimulus would help.

The Reserve Bank holds a special meeting on Thursday to cut interest rates to an effective lower bound of 0.25 per cent and adopt new measures to shore up the economy. The bank is expected to begin buying 10-year bonds, to ease longer-term interest rates. Mr Richardson said the measures were to be applauded but were not a saviour for the economy.

Already, events are cancelled, office workers are working from home, and restaurants and bars are putting off casual workers. Virgin Australia has suspended all international flights.

"Do not travel abroad, do not go overseas," Mr Morrison said. "That is a very clear instruction. For those of you who were thinking of going overseas in the school holidays, don't."

The new ban on indoor gatherings doesn't affect prisons, workplace, shopping centres and supermarkets, which are considered essential. Nor does it impact schools, which the government insists must stay open.

But churches and other places of worship must comply, including with a 1.5 metre social distancing guideline.

Outside, gatherings are allowed up to 500 people.

Nationally, Chief Medical Officer Brendan Murphy said hand-shaking must now stop.

"No more hand-shaking, no more hugging, except in your family," he said.

As the economic impacts of the coronavirus hit home, the health impacts are also being felt, with cases in Australia rising fast, despite limited testing. By Wednesday evening, 454 cases had been confirmed, up by 79 in just one day, with a sixth person dying, and a third person being diagnosed in Canberra. Cases are 11 times what they were a fortnight ago, when just 41 had been diagnosed.

Debate continues in medical circles about whether Australia should expand testing beyond people who have been overseas or in contact with cases, with Australian National University professor Kamalini Lokuge warning that "many thousands, perhaps hundreds of thousands of people, could die unncessarily because of lack of widespread testing.

New limits have been imposed on aged care, with visitor numbers limited to just two people at a time and visits are only allowed in a resident's room or outside. Social activities and entertainment are banned in aged care homes, and no one aged 16 or younger is allowed in an aged care home without a special exemption, such as when someone is dying.

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Mr Morrison warned that disruption would last at least six months.

"Life is changing in Australia as it is changing all around the world," he said.

"This is a once in 100-year type of event. We haven't seen this sort of thing in Australia since the end of the first world war."

But he urged people to stop bulk-buying.

"Stop hoarding. I can't be more blunt about it. Stop it. It is not sensible, it is not helpful and it has been one of the most disappointing things I have seen

Stop doing it. It's ridiculous. It's un-Australian, and it must stop," he said.

Schools would remain open. If they closed, tens of thousands of jobs would be lost, and the availability of health workers would be hit by 30 per cent, he said. "That will put peoples lives at risk. Let's keep our heads when it comes to this. There is a national public interest here in keeping schools open. And our advice is it's not being done at the detriment of the health of any children."

Twenty thousand student nurses in Australia will be mobilised into the workforce, Mr Morrison said.