School's out in more states to slow virus

However, top health officials say it could be one week until the effect of a second wave of shutdowns, which began on Thursday, is seen in reduced case numbers.

The number of confirmed cases in Australia has risen to 2793 and health officials are begging Australians to stay at home if they are sick in any way, and to keep their distance from other people even if they're healthy.

Australia has tested more than 178,000 people and deputy chief medical officer Paul Kelly says the rate of positive tests is low, at about 1.5 per cent.

"That again demonstrates, firstly, that we're doing a lot (of tests). Secondly, it convinces me that we're finding the ones that we need to look for," he said on Thursday.

The 370 new cases since Wednesday compares with a rise of 290 in the previous 24 hours.

Three Victorian men and one from Western Australia, all aged in their 70s, were confirmed on Thursday as Australia's latest fatalities.

Queensland, South Australia and Western Australia joined Victoria and the ACT in moving school holidays forward to give teachers time to switch to online learning.

Teachers will still be at schools so parents who have essential jobs, such as healthcare workers and supermarket shelf-stackers, can send their children.

But all other students are being asked to stay home.

The nation has already had two waves of business closures this week - leading to thousands of people losing their jobs - in a bid to stop people gathering in large numbers or in closed spaces.

Thousands more businesses were shuttered on Thursday and many large retailers stood down staff and shut down stores voluntarily.

Billionaire retail mogul Solomon Lew declared his company Premier Investments would not pay rent to landlords during a month-long shutdown of brands including Smiggle, Peter Alexander, Portmans and Just Jeans.

NSW and Victorian leaders are foreshadowing further moves, potentially including a full lockdown, if the increase in new cases doesn't slow.

The ACT has said it will follow whatever surrounding NSW does.

NSW Premier Gladys Berejiklian says the success of these measures would be judged by the number of community-to-community transmissions of COVID-19, rather than total case numbers.

"I'm saying to the community that if we're not convinced we've had a sufficient amount of success, NSW will have to take further action and that's a position I've been clear on from day one," she told reporters.

"If there's a significant shift ... you know you need to take further action."

But NSW chief health officer Dr Kerry Chant said the full effect of the second stage of shutdowns wouldn't be known for some days.

And Professor Kelly said it should be enough if people heeded the message to stay home.

"We can't stop this completely unless we all stay at home and the lights go out and no one has anything to eat," he said.

"We have to have some sort of sense of what we can and should do there, of minimising as much as possible what can be done to stop the spread."

But he warned tougher social restrictions would be needed if people didn't take social distancing seriously.

"If you're sick, stay at home. If you're in quarantine, you stay at home. If you're in self-isolation, you stay at home. If you are a contact with someone with COVID-19, you stay at home. If you have just come back from overseas in the last 14 days, you stay at home.

"I don't know how much clearer I can make it, seriously."

The federal government has been tinkering with restrictions in place to slow the spread of coronavirus.

Haircuts can now be longer than 30 minutes and the 10-mourner limit on funerals can be eased in cases of hardship.

Labor says making changes 48 hours after the restrictions were announced just adds to people's confusion.

"It's no good for the prime minister to blame Australians for not following the rules when the rules are so complex and confusing," health spokesman Chris Bowen told reporters, calling for "clearer, simpler and stronger restrictions".

Australian Associated Press