Travellers who can't convince border officials they have adequate arrangements for self-isolation could be sent home, Ministry of Health Director-General of Health Dr Ashley Bloomfield says.

New Zealand's total number of people with coronavirus remains the same with no cases reported, he said. "The tally remains the same, eight confirmed and two probable cases," he said on Monday.

Arrivals at the airport were being questioned before they reached the immigration desk, Bloomfield said, to make sure they have arrangements for self-isolation.

AP A microscope image from the US National Institutes of Health shows the Novel Coronavirus.

"They need to be able to demonstrate what their arrangements are. We will facilitate them making arrangements."

If they weren't able to convince officials, authorities may make arrangements to sent them back to the country they flew in from.

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The ​Ministry of Health has not begun considering prosecution of any specific cases of people who have refused to self-isolate, but Bloomfield said fines and enforcement options were being considered by a cross-government team.

"There is a range of approaches that can be taken, and we're looking at all of those," he said. "Rest assured, the medical officer of health can require people to be in self-isolation … and if needs be can call on police to assist in enforcing that."

He said several thousand travellers had arrived after the 1am deadline. But there had been a drop in the number of people flying in to New Zealand.

"In Auckland usually on a Monday morning there would be around 2400 people and this morning there was 1000, so there's already been a significant decline in the number of people arriving."

EXISTING CASES

The Australian man who was visiting Wellington remained symptom-free. He has moved from the hotel he was staying in and is now in self-isolation with two family members.

The public health unit would release the places he attended need be, he said. Wellington cafe Milk Crate has confirmed the man visited on Saturday.

New Zealand's eighth case, a Danish woman in Queenstown, had been discharged from hospital and was recovering in self-isolation.

Contact tracing for people possibly exposed to coronavirus on an airplace has changed, with a larger number of surrounding passengers now being considered close contacts. The people in such seats on the flights of recent cases were being contacted, Bloomfield said.

A passenger on the Golden Princess cruise ship tested negative, and the cruise ship had now left New Zealand waters.

The cruise ship in Wellington, and other cruise ships which have been in New Zealand waters, were being cleared by health officials. All ships had health staff on board them, Bloomfield said.

TESTING EXPANDED

Testing had been expanded to people who have a fever of 38 degrees Celsius or over, or symptoms such as a cough, he said.

Previously it was a combination of a fever and other symptoms.

The person's travel history is also considered.

SELF ISOLATION 'BEST TOOL'

Bloomfield said self-isolation remained one of the most useful tools to stopping widespread outbreaks. "Every situation is different, but at its most basic point, it means staying home if you are sick."

He was confident there is no community outbreak in New Zealand at this stage.

For people self-isolating after being overseas, Bloomfield said, "you can still enjoy biking, or walking, or running, alone".

There was no problem having a conversation with people who drop off food, for instance, but maintain a distance of two metres, he said.

"Yes, of course, you will be sharing your home ... but even inside your own home you can avoid close contact."

Minimise the time spent in shared spaces, he said, and keep those spaces well ventilated. "Don't share beds, linen".

He said people voluntarily going into self-isolation, such as Government minister Tracey Martin, MP Chris Bishop, and members of the New Zealand cricket team, had made a decision that was "commendable".

Healthline received 4500 calls after the announcement of self-isolation orders on Saturday. This was four times the standard call rate. Calls were being prioritised, he said.

"Don't call Healthline for travel advice, please ... don't call Healthline about whether you should attend an upcoming event, call the event organiser," Bloomfield said.