Declaring a human biosecurity emergency, and the first level four travel warning in Australia’s history, Morrison emphasised the threat of COVID-19 required unprecedented measures that may still be ramped up.

People have been urged not to travel overseas, and to come home if already abroad, while essential services are being safeguarded and new rules introduced to support supermarkets and the casual workforce.

Governments have already urged against non-essential gatherings of 500 people or more. After a national Cabinet meeting on Tuesday night, governments agreed to keep that restriction for outdoor events but tighten the indoor controls to non-essential gatherings of 100 people or more. The new measures apply from today.

“This is a once-in-100 year event,” Morrison told reporters at Parliament House in Canberra.

“We are going to keep Australia running. We are going to keep Australia functioning. It won’t look like it normally does, but it is very important that we continue to put in place measures that are scalable and sustainable. There is no two-week answer to what we are confronting. There is no short-term quick fix.”

There are already 454 confirmed cases of COVID-19 in Australia, including 94 in Queensland, and pockets of community transmission in places like Sydney and the Gold Coast. Experts have advised the government to slow the spread of the coronavirus now to help the health system deal with a more manageable peak and protect the most vulnerable.

So far, essential gatherings have been allowed to continue, including those at shopping centres, supermarkets, office buildings, public transport, factories and mine sites, however this may change. Queensland and other state governments are preparing evidence-based advice for pubs, clubs, cinemas, restaurants and cafes – even wedding and funeral organisers.

While there will be restrictions on visitors to aged care facilities – operators will have some discretion in end-of-life situations – governments have so far resisted ordering all schools to close.

“The health advice is that schools should remain open, that is the health advice,” Morrison said, noting that schools also remained open in Singapore.

Morrison emphasised that sick children should be kept away from school, but young people generally were considered at lower risk of the more severe cases of COVID-19 and should instead be encouraged to wash their hands and practice self-isolation where possible.

Closing the schools, the Prime Minister said, would keep them off-limits for six months or more with “severe” ramifications for society and the economy, including the loss of tens of thousands of jobs where parents had to stay home.

Morrison said modelling also suggested that if parents needed to stay home the health system itself would be left with 30 per cent fewer workers.

“Let’s keep our heads as parents when it comes to this, let’s do the right thing by the country and by each other and follow the proper advice. There is a national public interest here in keeping schools open and our advice is that is not being done at the detriment of the health of any child.”

More tests and protective equipment have been imported, and Morrison said restrictions on international students doing nursing degrees would be lifted to allow 20,000 to join the workforce in some capacity. Australian medical students, and recent retirees, are already being rallied to bolster the health system.

Amid ongoing concerns over conflicting information, and false claims of a pending shutdown circulated on social media on Tuesday night, Morrison called on Australians to listen to authorities and the experts they are taking advice from. His comments, on this and other issues including the arguments against school closures and hoarding, were echoed by state and territory leaders, including Queensland Premier Annastacia Palaszczuk. Governments are making a concerted effort to improve and coordinate communication.

Morrison and Palaszczuk said the health response was the priority but economic support was also under constant consideration.

From a sparsely populated state parliament, Palaszczuk urged people to get used to change.

“It will continue to change by the day and by the week over the immediate and foreseeable future as we deal with and confront the coronavirus crisis, an event we have never seen in our lifetimes, an event that is a once-in-100 year event,” the Premier said.

“Today, I want to assure Queenslanders that we will get through it. We will get through it by working together, by supporting each other, by keeping calm heads, and by listening to accurate, expert advice. Australia will continue to keep running, Queensland will continue to keep running, but this will take at least six months for us to get through and it may be longer.”