Extreme measures will need to be taken to manage the inevitable coronavirus pandemic , Victoria's Premier has said.

The Victorian COVID-19 plan will look to manage the surging demand that coronavirus will put on the health system.

"We are told by the experts where we are going to reach a phase that there will be so much transmission among Victorians that we will need to take extreme measures," Premier Daniel Andrews said.

The coronavirus as seen under a microscope. (AP)

"We will need to ask Victorians things we have never asked them before."

That means cancelling major sporting events, requiring entire economic sectors to work from home , and calling recently retired health professionals to return to work.

It comes as three new cases of the virus were diagnosed in the state today.

There is some question as to whether coronavirus will lead to the cancellation of the Melbourne Grand Prix. (The Age)

At present, the premier has not called for the cancellation of the Melbourne Grand Prix next week, or the launch of AFL season the week after.

"The reason the Grand Prix's not cancelled next week is because the advice says we don't need to do that today. That advice may change," he said.

Mr Andrews said it was a case of when, not if, the extreme measures will need to be introduced to manage the pandemic.

The global spread of coronavirus. (Graphic: Tara Blancato)

That decision will be made by the premier acting on the advice of the Chief Medical Officer.

"That disruption will be significant. It will hurt our economy," the Premier said.

"But it means less Victorians will be sick, which means less Victorians will be gravely ill."

Health Minister Jenny Mikakos said retired paramedics, nurses and doctors should consider whether they can return to work to ease the strain on the health system.

How does coronavirus affect the body? (Graphic: Tara Blancato)

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

"This is a time where we all need to come together."

Eighty per cent of COVID-19 patients do not need hospital treatment and can recover at home.

But the fatality rate is between one and four percent, and about 20 per cent will need serious treatment.

New cases

The three new cases include two men in their 70s, one who travelled from the United States, and another from Singapore.

The first man presented to hospital immediately upon landing on Flight VA24 from Los Angeles on March 8.

He is isolated at home.

The second man became unwell on February 27 while in Egypt. He had earlier travelled to Israel, Egypt and Jordan.

He returned to Melbourne from Singapore on March 6 on Flight EK404.

On March 6 he attended South Melbourne Market between 8.30am and 10am.

The next day he was at the Albert Park Hotel between 6pm and 10pm.

He is now in home isolation.

A third caught the virus from a family member who was already sick.

The woman in her 50s is the first case of patient-to-patient transmission in Victoria.

She is recovering in isolation at home and her condition is mild.