It estimated that 64 percent of the population would become unwell from the virus SARS-CoV-2, while 32,000 people would need hospitalisation and 14,000 could die. This would be less severe, however, than the 1918 influenza pandemic, which killed 9000 of 1.149 million people in New Zealand at the time.

"If interventions were intense enough, however, in some scenarios the epidemic peak could still be suppressed or pushed out to the following year (at which time a vaccine may be available)" the report concluded.

It suggests that 89 percernt of the deaths would be people above the age of 60.

Prof Wilson told RNZ that worst-case scenario is based on a model where the country's hospitals and ICUs can function - something that other countries have had issues with. 

"The death rate would certainly increase dramatically if hospitals and ICUs were overwhelmed," he said.

The professor said New Zealand's current strategy - revolving around a nationwide lockdown which requires people to stay indoors unless it's absolutely necessary to go out - is the best thing we could be doing. 

"The best case is the current strategy that New Zealand has adopted of eliminating this pandemic virus and if we are successful, and we will start to see that in the coming weeks, that will definitely be the best outcome because it may mean relatively few hospitalisations and deaths and it might mean we will be able to open up to the economy, though maintaining very good border control until we get a vaccine," he said.

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Being an island nation with strong control of our borders was extremely helpful, Prof Wilson said.

The report was released by the Ministry of Health on Tuesday, with Director-General Dr Ashley Bloomfield saying it reinforced the importance of the lockdown measure.

"The modelling shows that without the actions currently being taken, the uncontrolled spread of COVID-19 would exact a high price in New Zealand in terms of its impact on our health services, including our intensive care units, and deaths," he said.

"Even with the sorts of strong measures we have in place to stamp out the virus the modelling is still predicting there could be a heavy toll on our health system and loss of life. That shows how seriously we need to take the virus, stick to the rules of the lockdown and maintain measures that reduce the risk of the virus entering the country."

Over the lockdown period, Prof Wilson said the number of cases resulting from community transmission - where the infected individual has no clear link to another case - would be crucial in showing the effectiveness of current measures. 

However, he said to get a better idea of how widespread community transmission may be, greater testing was needed. 

On Monday, the Ministry of Health said the daily average of tests undertaken over the last week was 1728. While that number is far higher than it was two weeks ago, Prof Wilson says it should still be several times higher. 

"We need to do far more testing and far more vigorous contact tracing to be rapidly on the track of elimination," he told RNZ.

"Basically, anyone turning up to an emergency department or a hospital with any respiratory condition should be tested. We should be doing random testing in different communities."

While the worst-case scenario presented by the research is grim, a previously released paper from Te Punaha Matatini suggested 80,000 New Zealanders could die if the lockdown wasn't put in place. 

Currently, 589 people have the virus in Aotearoa, with one death. Lockdown measures are to stay in place for at least another three weeks, before being reviewed. It is possible the lockdown will be extended, either nationally or in regions of the country which continue to have community transmission.

Authorities have warned the number of cases will continue to rise for at least another week as people who caught the virus before the lockdown become symptomatic and get tested.