Health professionals and academics have welcomed the Government's move to almost shut New Zealand's borders, as the coronavirus pandemic worsens around the world. 

More than 156,000 people have now been confirmed to have the disease, caused by a virus called SARS-CoV-2, and more than 5800 have been killed. 

From midnight Sunday, only people arriving from the Pacific Islands will be able to get off the plane and walk around New Zealand freely - everyone else, including citizens and residents, will have to go into self-isolation for 14 days. 

The move came after New Zealand's sixth case was confirmed - a person who'd recently arrived from the US, where the virus is spreading person-to-person.

"These actions are bold, but justified on the basis of the information coming out of other countries and the opportunities we have as an island nation with few confirmed cases of COVID-19 so far," said University of Otago clinical microbiologist  David Murdoch.

"The experiences of countries such as Singapore and China indicate that an aggressive approach, involving multi-pronged surveillance and containment strategies, has paid off by slowing the growth of the outbreak within their jurisdictions."

People who go into self-isolation will be monitored by health officials, Prime Minister Jacinda Ardern said on Sunday. Those who refuse to comply may be forced to by police, she said. 

"We can put people on the door to make sure you don't leave. Now those are powers we haven't had to use and I don't anticipate having to use - but they do exist," she told Q+A.

Michael Baker of the Department of Public Health at the University of Otago, Wellington, said the strict measures will be "widely welcomed".

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"These measures greatly strengthen the 'keep it out' component of our pandemic plan. They also show support for the wider goal of containment. This is the path being successfully followed by some countries overseas, such as Singapore and Taiwan, which have also managed to keep the numbers of COVID-19 cases at low levels."

University of Auckland microbiologist Siouxsie Wiles, who has been the public face of the New Zealand scientific community in the past couple of weeks, says Ardern "is doing exactly what is needed to limit the spread of the virus".

"Now we should start preparing ourselves for how long these measures may be in place."

She warned a vaccine could be a year or two away.

"If we turn our back for a minute, we’ll could find ourselves in the position of countries like Italy."

Italy has the highest number of confirmed cases outside of China, where the virus first appeared. China has almost wiped out person-to-person transmission, earning praise from the World Health Organization. Most of its new cases are now from people bringing it into the country.

Joshua Freeman, a doctor at the University of Otago, Christchurch, said the Government's move "may seem radical but the stakes for population health are very high". 

"If we don't keep on top of community transmission and 'flatten the curve' our healthcare systems will be comprehensively overwhelmed."

'Flattening the curve' is the goal of keeping transmission in the community slow, so health services aren't overwhelmed. 

"That puts a real strain on your public health system," said Ardern.

"We won't be able to stop cases in New Zealand, but we can try and slow them, which is exactly what these decisions are all about."

National Party leader Simon Bridges welcomed the move too, saying his party wants to "work with the Government to see much more testing and other health related measures such as the urgent gearing up of our health system for the many patients coming".