Victorian Premier Daniel Andrews says it is only a matter of time before schools close across the state and large sporting and cultural events are cancelled to combat the spread of coronavirus.

Key points: The new measures would be introduced once there was a significant number of community transmissions of the virus

The new measures would be introduced once there was a significant number of community transmissions of the virus There are now 18 cases in Victoria after three more were confirmed on Tuesday

There are now 18 cases in Victoria after three more were confirmed on Tuesday Seven hospitals are now testing for coronavirus and Carey Baptist Grammar will be closed for the rest of the week

While the Premier said the State Government had no immediate plans to cancel football matches or the Grand Prix, he said "extreme measures" would likely need to be taken in the future, when there is a significant number of transmissions of the disease within Victoria.

"We will need to ask Victorians to do things we have never asked them to do before," he said.

Carey Baptist Grammar School in Melbourne cancelled classes on Tuesday and will remain closed for the rest of the week after a staff member tested positive for coronavirus.

But Mr Andrews said it would not be the only school affected and the state was planning for the next phase of the spread of the virus.

"Part of that plan is the inevitability that we will get to the point that rather than one school being closed, all of our schools will be closed," he said.

"Rather than people simply distancing themselves and quarantining themselves, we may have entire sectors, entire workforces where people are working from home."

Mr Andrews said the Victorian Government was planning for coronavirus to have a major impact across the state, but the measures being planned would help keep people safe.

"The disruption will be significant, it will hurt our economy, it will inconvenience many, many people," he said.

"But ultimately, the experts tell us, that less Victorians will get sick and therefore less Victorians will be gravely ill once we move to that pandemic phase."

Victoria is ramping up its ability to test for the virus. ( ABC News: Ron Ekkel )

He said he could not say exactly when the spread of coronavirus would reach a point that such measures would be necessary.

On Tuesday Victoria confirmed three more cases of coronavirus, bringing the total number of cases in the state to 18.

Mr Andrews said the decision to introduce social distancing measures would be taken on the advice of Victoria's chief health officer, Brett Sutton.

Quarantining measures won't stop outbreak, chief health officer says

Dr Sutton said he would be closely following the spread of "community transmissions" to decide when social distancing measures were required.

Community transmissions are when people contract the virus, but health authorities are unable to trace the spread of the disease back to someone who has arrived in Australia from overseas.

"When we see a lot of community transmission, maybe the majority of cases are community transmission, that is a real time to reflect on the fact that your identification, isolation and quarantining measures are not going to hold it," he said.

He said that would be a sign of an uptick of an epidemic curve and social distancing would become the critical measure to limit the spread of the disease.

People queued up outside the Royal Melbourne Hospital to be tested for the virus. ( ABC News: Ron Ekkel )

Dr Sutton said he would like to see all of the states discuss the closure of public places and events at a national level.

"I think if we are going to bring all Australians along with us we need to be doing it in concert and doing it with a single voice," he said.

Dr Sutton said modelling showed the virus would peak about 10-15 weeks after community transmission occurs, but said it would be difficult to identify when that had happened.

He said it may have happened already.

He called for businesses to make plans to ensure sick staff members were not in the workplace, including running their operations with reduced workforces and for staff to work from home.

Dr Sutton said social distancing measures would help reduce the spread of the disease, and the number of people who die from it.

He said that would include cancelling large events, proactive school closures and changes to public transport.

Pandemic to test health system, Minister says

Victoria's Health Minister Jenny Mikakos said Victoria was ramping up its ability to test for coronavirus.

She said a hotline that has been set up to help those worried about having coronavirus would add 100 staff by Friday.

Ms Mikakos said there were seven hospitals screening for coronavirus and planning was underway to help the health system cope with a forecast increase in cases.

"This likely pandemic that is really a matter of time now, is going to test our health system," she said.

Ms Mikakos said retired medical workers like nurses and paramedics could be asked to return to work to help the state through a coronavirus emergency.

She said medical workers "will be really pushed and stretched as they will be confronted with a huge increase in demand".

Ms Mikakos said the state had already put in orders for extra equipment and machines to cope with a surge in cases.

A plan published by the Victorian Government to outline its response to the outbreak, says modelling shows a coronavirus pandemic is likely to coincide with Australia's flu season.

It says "the effects of both diseases may be felt simultaneously".

While the government plan says the trajectory of the virus is highly uncertain, it raises the prospect of the effect of both diseases being felt simultaneously.

"Healthcare services and health professionals must prepare for the possibility of a significant and prolonged increase in demand for healthcare services," it says.

Carey Baptist Grammar cancelled classes after one of its teachers tested positive for the virus. ( ABC News: Patrick Rocca )

School to remain closed

Carey Baptist Grammar School principal Jonathan Walter emailed staff on Tuesday, saying the school would remain closed for the rest of the week.

He said a teacher who worked in the middle and senior schools at the college had been diagnosed with coronavirus.

The school initially contacted families on Monday night to cancel classes for Tuesday but the closure has now been extended.

Mr Walter said the school would remain closed so authorities could "map any potential exposure to Carey community members".

He said the Health Department would be in contact with anyone identified as having close contact with the teacher, which was defined as 15 minutes or more of face-to-face contact, or two hours or more in the same closed space.

Mr Walter said the school would contact anyone who had been identified as having casual contact with the teacher, which included people with less than 15 minutes face-to-face contact, or less than two hours in a closed space.

"This is a challenging situation for families as well as staff and we are working to manage the broad implications of both the virus exposure and the temporary shutdown of the school," he said.

A Health Department spokesperson earlier confirmed the teacher's partner had been on the same flight from the US as Toorak GP Chris Higgins, who tested positive on Friday.

Footy could be played in empty stadiums

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 45 seconds 45 s Gillon McLachlan says round one of the AFL season will go ahead as planned despite concerns about coronavirus.

AFL chief executive Gillon McLachlan said if mass gatherings were suspended "then we will play games in stadiums with no crowds."

He said the AFL had a working group to deal with the issue and had listened to what the Victorian Government had said.

"Our advice at the moment is to push ahead as planned and round one will go ahead as planned with supporters," he said.

"But I think we take note of what was said today."

Asked if games could be delayed, Mr McLachlan said the league intended to stage every scheduled match.

"That is all I can say and we will continue to make the decisions we need to, to get that done," he said.

He encouraged fans to continue attending matches as long as that was allowed.

Ferrari sends smaller team for Grand Prix

Ferrari last won the Australian Grand Prix in 2018, but is sending a smaller team this year in the wake of the coronavirus outbreak. ( AP: Asanka Brendon Ratnayake )

The Australian F1 Grand Prix starts in Melbourne on March 12 and could attract tens of thousands of spectators each day.

The race's organisers have said there would be additional precautionary measures in the wake of the coronavirus outbreak, including more hand-washing stations and closer cleaning of facilities.

A scaled-back team of 150 will attend the race from Ferrari's northern Italian base, the last of whom were expected to arrive on Tuesday.

The Bahrain Grand Prix, due to be held later this month, recently announced that fans would be banned from the track to reduce the risk of transmission of the virus.