Australia has seen 100 confirmed cases of coronavirus and more than half have recovered as the government assures people they can only catch it once.

With more than half Australia's 100 coronavirus patients already recovered, federal Health Minister Greg Hunt says it's unlikely anyone would be infected a second time.

Mr Hunt says neither will it be necessary to introduce a country-wide travel ban, a measure which has affected 60 million Italians, although Qantas has slashed flights by a nearly quarter and the temporary closure of schools is likely to become more widespread.

The government would also be reviewing its travel advice to Italy where more than 9000 people have contracted COVID-19 and 460 have died, Mr Hunt said on Tuesday.

Across the world there are an estimated 114,000 cases in 107 countries, with 1000 recorded deaths.

Chief Medical Officer Brendan Murphy said it was highly unlikely people could catch the virus more than once.

"I think that's a very important message to Australians," Mr Hunt added.

"So now is the moment of pressure ... this is a once in 50 year challenge that we face."

Three Australians have died from coronavirus, with states and territories setting up specialist clinics as the government looks to combine information into a smartphone app.

The Department of Foreign Affairs and Trade has followed US authorities in advising citizens, especially those with underlying health concerns, to reconsider taking an overseas cruise as the outbreak continues to spread.

Professor Murphy said there had been some confusion about who needed to be tested, saying it was only returned travellers from overseas with symptoms like a cough or sore throat.

Three schools in NSW and Victoria shut on Tuesday after three students tested positive to COVID-19, with similar temporary closures likely to become more widespread.

"School closures, I think, will become the norm as we go ahead but we are doing everything we can to keep our children safe," federal Education Minister Dan Tehan told Nine's Today program.

The minister was asked why schools were being closed for a day or two, while people with or suspected of having the virus are being told to self-isolate for two weeks.

"The schools have been closed for a day so they can be thoroughly cleaned," he replied.

Sydney is considered the worst-hit city.

Qantas has slashed the capacity of its international flights by almost a quarter for the next six months due to the virus' impact.

The decision means 38 planes will be grounded.

In coming days the government is expected to announce private sector involvement in providing pathology services and new advice on the testing of healthcare workers.