Hunter New England Health said on Saturday that it did not know how or where the woman had contracted the coronavirus but she had attended the Mater hospital's oncology unit as an outpatient between March 4 and 12.

"Anyone who attended the Calvary Mater Newcastle Radiation Oncology Unit between 4 March and 12 March 2020 should be alert for fever or respiratory symptoms," HNEH said.

"If they develop any of these symptoms, they should contact their GP or present to an emergency department."

The health service was contacting patients and staff who might have been in contact with the woman.

The woman has not travelled internationally recently and is classified as a local transmission case.

HNEH's director of health protection, Professor David Durrheim, said the service had identified anyone else who might have been in close contact with the woman and they were in isolation for two weeks.

"We're still investigating the transmission source. Obviously, we try to find the source of every single case, and there's a rigorous process for doing that," he said.

"Whether she was infected by a visitor to Australia or some other person, we do not know."

Professor Durrheim said health services were not revealing how many people had been in close contact with COVID-19 patients.

He said the vast majority of transmissions were from people who had already developed COVID-19 symptoms, which helped identify infection sources.

HNEH was "providing care and support" to the woman, who also was in isolation at home and doing well.

"They will be contacted every day by the public health unit to check that they are well, and any contact who develops COVID-19 symptoms will be tested for the infection."

HNEH said there was no connection between the second case and a Hunter man in his 70s who developed COVID-19 this week after being in Italy.

Professor Durrheim said Australians owed a debt of gratitude to people forced into isolation for two weeks.

"They're making a wonderful contribution," he said.

"It's not easy to be in the home quarantine, but so far we've found that everybody who has been in close contact with cases has been really, really willing to make their contribution on behalf of the community."

Meanwhile, Apple announced it was closing all its stores around the world, except in China, for the next two weeks.

The number of coronavirus cases passed 200 in Australia on Saturday.

This story originally appeared on the Newcastle Herald