Fourth case of coronavirus in Victoria

A fourth case of coronavirus has been confirmed in Victoria, as health authorities wait on more than a dozen other test results for the deadly illness.

A Melbourne woman, aged in her 20s, became ill after flying home from Wuhan a week ago, but health authorities say she was not infectious en route and is recovering in isolation at home.

It comes as Monash University pushes back its start date for the first semester by a week as a precaution against the spread of the virus.

"We've had to make some difficult decisions for the safety and wellbeing of our staff, students and the wider community," the university said in a tweet on Friday.

It comes after the World Health Organisation declared the virus a public health emergency and ahead of the evacuation of Australians stranded at the epicentre of the outbreak to Christmas Island.

More than 250 people have died in China so far and nearly 12,000 cases are confirmed, that country's state media says.

Back in Victoria, authorities are waiting on 13 test results for coronavirus after giving 149 people the all-clear.

The latest confirmed patient became ill two days after arriving home on January 25.

She was seen by doctors at a Melbourne hospital five days later before being cleared to recover at home.

Since then, the woman has remained in isolation and had no visitors so authorities do not believe she has exposed others to the virus.