Health authorities in New South Wales are investigating whether one person has contracted the deadly coronavirus just hours after a flight touched down in Sydney from the virus epicentre in China.

Key points: Passengers with symptoms of the virus will be taken to Westmead Hospital

Passengers with symptoms of the virus will be taken to Westmead Hospital It has already killed 17 people in China

It has already killed 17 people in China And, there have been hundreds more infections

NSW Chief Health Officer Dr Kerry Chant said testing will be rapidly undertaken and authorities able to exclude or confirm the case within "a very short timeframe".

The virus originated in the Chinese city of Wuhan, and has killed 17 people.

Wuhan has since been placed in lockdown.

But the virus has already spread to other Chinese cities, while abroad, Thailand has confirmed four cases, and the United States, Singapore, Taiwan, South Korea and Japan have each reported one.

A flight from Wuhan arrived in Sydney on Thursday morning and passengers were screened individually for symptoms of the highly contagious bug.

Australian authorities took no chances when China Eastern flight 749 from Wuhan touched down, stationing biosecurity officers and border security staff at the terminal to interview passengers.

China Eastern Airlines flight crew walk through Sydney Airport. ( AAP: Joel Carrett )

None of the passengers on that flight were found to be ill when screened but were warned to contact a doctor should symptoms begin.

Four hours after the flight took off, Chinese officials made a bombshell announcement the city of 11 million people was being locked down in a bid to contain the virus, which has already killed 17 people and put hundreds more in hospital.

Bus, subway, ferry and long-distance passenger transportation networks will be suspended from 10am local time (1pm EDT), and the airport and train stations will be closed to outgoing passengers, state TV said.

Sydney is the only Australian city with direct flights to Wuhan.

The services, which were launched in 2017, run three times a week.

Kevin Ouyand shows the information he was given when he arrived in Sydney from Wuhan. ( ABC News: Liv Casben )

Sydney father-of-two Kevin Ouyand returned on the flight after spending one night in Wuhan where he said he wore a mask the whole time.

The 40-year-old said he was worried about being in Wuhan as the situation was "very serious".

He said all passengers on board flight CES749 were screened on arrival at Sydney and that and everyone, including the flight crew, wore masks.

Mr Ouyand said he will continue wearing his mask at home for the next 10 days.

"I need to protect my family members," he said.

One man who was at Sydney Airport to pick up his girlfriend, who was on the flight, said she was "very lucky" to have got out.

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Prime Minister Scott Morrison said he understands Australians may be feeling anxious but every precaution was being taken.

"I think it's important that we continue to get good information, we go about our normal course of business, but just being aware of those risks and to the extent that they are there," he said.

Australia's Chief Medical Officer, Professor Brendan Murphy, said the World Heath Organisation had not yet declared coronavirus a public health emergency of international concern but every state and territory was well prepared.

"Every one of our state public health departments has a designated isolation facility and clearly established protocols to get people to those facilities. The tests are being sped up," Dr Murphy said.

He said that most of the mortalities had been people with existing chronic diseases and early evidence suggested coronavirus was not as severe as Severe Acute Respiratory Syndrome (SARS) or Middle East Respiratory Syndrome (MERS).

Hospitals in Wuhan are reportedly dealing with huge numbers of sick patients, and on Wednesday the local government issued an order for everybody to wear masks in public.

The order to shutdown Wuhan came the day before Chinese New Year.

Passengers arriving in Sydney say they are relieved to be out of Wuhan. ( ABC News: Liv Casben )

Dr Jeremy McAnulty, the executive director of health protection at NSW Health, said the coronavirus seemed to be less infectious than the SARS outbreak that killed more than 700 people in 2003.

"At the present we believe the risk of transmission of the infection, should it occur in New South Wales is probably pretty low," he said.

"The situation is evolving from day to day there are no cases in New South Wales identified.

"But we're preparing that the health system, GPs, emergency departments and so on should cases occur in New South Wales."