Coronavirus could infect billions - Kiwi public health expert

A professor of public health at Otago University says millions or even billions of people could eventually become infected by coronavirus.

Dr Michael Baker says New Zealand's decision to extend its travel ban on flights to and from mainland China will buy the country more time in planning for how to deal with the virus when it eventually gets here.

"New Zealand is at the 'keep-it-out phase' of its pandemic plan, and every passing day gives us more opportunities to plan our response," Dr Baker told Newshub.

There remains much about COVID-19 - the official name for coronavirus - that experts don't know, including just how dangerous it is, Dr Baker said.

"A portion of people die, we just don't know how big that proportion is. And that's something that's starting to become a very important piece of knowledge because we're talking about millions, ultimately billions of people getting infected."

On Monday, Prime Minister Jacinda Ardern said it was "not realistic to assume" the virus won't reach our shores, saying there was a "very high chance" a case would be confirmed here at some point.

"Given the spread and the reach, given that we aren't talking about just cases in mainland China - you are seeing reasonably significant outbreaks outside of that - there is a very high chance of having a case in New Zealand," Ardern told The AM Show.

Fears the virus will become a pandemic have risen in recent days, after a spike in new cases reported outside of mainland China. 

Iran, Italy and South Korea, in particular, have had surges of confirmed cases.

The World Health Organisation said it was "too early" to speak of a pandemic but that the outbreak remained a global emergency.  

The virus has had a massive economic effect worldwide, affecting global supply chains and leading to many airlines halting flights to and from China.

In New Zealand, tourism operators are feeling the pinch, as are numerous other sectors.

It's feared that our logging export industry could come to a complete stop due to the outbreak, as China's ports are full to the brim with stock.

Forest Owners Association president Peter Weir says there is four months of inventory sitting at ports.

"The price is actually not known at the moment because the sawmills haven't restarted because of the virus, but when they do the expectation is prices will continue to go down," he told Newshub. 

"They've reallocated wood from export to domestic, but there's only so much wood the domestic market can take."