Cars pressed into service as makeshift ambulances during the 1918 influenza outbreak in Wellington.

If New Zealand were to be hit by an extreme pandemic, we should shut the borders to trade and tourism to save lives, Wellington researchers say.

Researchers from the University of Otago in Wellington have done a cost-benefit analysis of total border closure in the face of potential future pandemic threats and found a major lethal pandemic would be best met with swift action from Government to temporarily seal us off from infected outsiders.

"You're talking about the extreme end of the range here. In most pandemics it wouldn't make sense," co-author Professor Nick Wilson from the university's department of public health said.

SUPPLIED Study co-author Professor Nick Wilson from the Department of Public Health at the University of Otago, Wellington.

The deadly Spanish influenza pandemic 99 years ago killed more than 8600 New Zealanders in two months, and some estimates said half of the country was sick, Wilson said.

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Even in the face of a complete end to exports and imports, the authors estimated New Zealand would save $54 billion by closing the borders provided that, if the borders remained open, 2.75 per cent of the population would otherwise die.

NEIL MACBETH/FILE The medicine depot in Cathedral Square, Christchurch, where the Government standard influenza medicine was supplied in 1918. (Historical image from the Weekly Press)

That's based on figures from various government agencies that state every year of a person's life is valued at $45,000, imports and exports are worth nearly $2b in total each week, and tourists bring in $125 per day.

To constitute a major pandemic, we'd have to see " lot of people dropping dead" around the world and a rapid spread of disease, Wilson said.

Wilson and co author Professor Michael Baker looked at different scenarios of death rates and pandemic levels alongside associated healthcare costs and valuation of life, versus potential lost tourism revenue and trade.

"New Zealand has done some pretty good pandemic planning but it has never done anything around border closure. We are saying if you want this work and the prime minister and cabinet have to make a decision within 24 hours - they have to know the processes," Wilson said.

"It would be a very hard call – but in the case of some severe pandemics it could save thousands of lives and huge costs from illness if border closure is rapidly achieved."

"Most of the deaths were from bacterial pneumonia, which in modern-day times could be treated. But in a pandemic situation where thousands are getting sick maybe there would be potential shortages [of medication].

"Modern medicine is geared for the usual run of the seasons with increased demand in winter - but it's not set up for this massive overload."

In 2009, the country was struck by a minor influenza outbreak, and ICUs around the country were stretched, Wilson said.

The pair considered the option of trade continuing, on the basis cargo ship crews did not need to leave their vessel.

Rolls-Royce has predicted crewless "drone ships" could be sailing the seas as soon as 2020, with sensors such as radar, lasers and computer programmes allowing the ships to pilot themselves.