First NSW coronavirus patients discharged

Two of the four NSW coronavirus patients have recovered from the potentially lethal infection and have been discharged from hospital.

NSW chief health officer Kerry Chant says the two other patients remain in hospital with the virus, while 20 possible cases are under investigation.

The two men discharged from hospital were no longer infectious, Dr Chant said on Thursday.

"Their symptoms have resolved completely," she told reporters.

"As an added precaution we have undertaken testing to confirm there is no virus detectable in samples taken from those individuals.

"They acquired the virus, they got better, and now they're not infectious."

Both of the discharged men had arrived from China: a 35-year-old who travelled to Sydney from Shenzhen and a 53-year-old who flew from Wuhan.

A 21-year-old female student from UNSW and a 43-year-old man remain in isolation.

Authorities in NSW have been ramping up testing for the virus in recent days, encouraging recent visitors to China to come forward even if their symptoms are mild.

Dr Chant said she would not be surprised if further cases of coronavirus are confirmed in NSW.

"I wouldn't be concerned if I found another case - that would reflect the veracity of our screening processes," she said.

Eight cases have been confirmed in Australia - four in NSW, three in Victoria and one in Queensland.

Negotiations are underway with Chinese officials to evacuate Australians locked down in the virus epicentre of Wuhan in Hubei province.