Health officials will track the thousands of Kiwis still returning from virus-struck China, after only a fraction voluntarily registered their return.

On Monday afternoon, Ministry of Health Director-General Dr Ashley Bloomfield said only roughly one in 10 of the 4500 people who had returned from China in the past week confirmed they were quarantining themselves in home.

In response, he said the ministry would collect people's contact details at the border and Healthline would then call them to check they were following the orders to self-isolate to prevent the spread of the novel coronavirus.

"We are working to get contact details for people who have travelled back from China and may not yet have registered and Healthline will be proactively contacting those people anyway."

Bloomfield also played down the significance of reports out of China that the virus was more contagious than previous thought, spreading through tiny airborne particles.

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He said it was already well-known that many respiratory virus, such as this coronavirus, could spread this way and this did not appreciably change the risk.

"These can be transported further distances but we are not talking about across rugby fields or large distance, but generally across a room."

"What is the management of that? The management of that is to ensure people that are unwell self-isolate and don't come into contact with other people."

MONIQUE FORD / STUFF The Ministry of Health's Director-General of Health Dr Ashley Bloomfield provides an update about the novel coronavirus outbreak.

As of Monday, at least 37,000 people have contracted the novel coronavirus, most of them in the central province of Hubei in China, with 814 dying as a result. Twenty-three other countries have now reported cases of the virus.

The number killed by the virus, first reported in the city of Wuhan in December, has now surpassed the 2003 Sars outbreak.

China's government has severely restricted the movement of 60 million people and round up infected citizens to be placed in mass quarantine.

In New Zealand, all foreign nationals who have travelled from or via mainland China in the past two weeks have been prevented from entering the country. New Zealand residents have been asked to quarantine themselves at home for 14 days after returning from mainland China.

DAVID WHITE/STUFF Tourists arriving in New Zealand wearing face masks. (File photo)

Meanwhile, Bloomfield said several people quarantined at the Whangaparaoa Military Camp, a training base in north Auckland, after being evacuated from Wuhan, China, have been tested for coronavirus after developing mild symptoms. None were infected and there remained no cases of coronavirus in New Zealand.

Bloomfield said there had been a surge in calls for people registering with Healthline after returning from mainland China.

In Japan, two Kiwis were among 61 people aboard the Diamond Princess cruise-ship who contracted the virus. The ship and all 3700 passengers, including 13 New Zealanders, have been in quarantine near Yokohama for five days.

There have been no reported cases in New Zealander to date, although the Ministry of Health said some cases were likely based on experience overseas.