New Zealand is currently tracking at "the lower end of some of the predictions" of how many cases and hospitalisations the Omicron outbreak may result in, the Prime Minister says.
Modelling released on Tuesday from COVID-19 Modelling Aotearoa - a group of experts including Prof Shaun Hendy and Prof Michael Plank - simulated several scenarios with differing rates of transmission, different start times, and different levels of booster vaccine uptake.
The group's work has not yet been peer-reviewed and was undertaken before the detection of Omicron in the community. However, it warns of the "significant strain" the variant may place on the health system in coming months.
Asked about the modelling on Tuesday, Jacinda Ardern said Omicron has only been a variant of concern for a matter of months, meaning that "much of what we are using is scenario-planning, rather than necessarily accurate forecasting".
She said that "at the moment" New Zealand is "tracking at the lower end of some of the predictions".
For the low transmission scenario - which the modelling report says is comparable with outcomes seen to date in South Australia - an outbreak which began on February 1 and where 90 percent of the eligible population get boosted would result in 1.5 million infections and 386,400 cases. That scenario would see the number of people hospitalised hit 11,500, with peak bed use of 800 and deaths reaching 460. It's the most optimistic model in the report.
It's important to note infections and cases are different, as many infections are never detected and therefore aren't recorded as cases.
Ardern pointed out that one of the key determinants in the models is around boosters uptake.
"The more we have of that, the more likely it is that we'll be on this end of the spectrum that's a bit more like South Australia than it is New York," she said.
If you take the low transmission February scenario where just 70 percent of those eligible get boosted, infections rise to 1.7 million, overall hospitalisations close in on 14,000 and deaths reach 560.
The high transmission February scenario (comparable to New York) with just 70 percent getting boosted could see up to 3.5 million infections, 31,000 hospitalisations and 1450 deaths.
New Zealand detected Omicron in the community on January 23 and moved to the red light setting, which still allows businesses to operate and people to leave their homes but places limits on gatherings.
More than two weeks later, 202 cases were recorded on Tuesday and 14 people are in hospital.
The Prime Minister said while cases are growing, vaccinations and the red light measures were slowing the spread. She noted that two weeks into the outbreak, the rolling three-day average is around 200 cases, lower than many predictions.
At the peak of Delta, Ardern said New Zealand had just under 100 people in hospital and a dozen in ICU. Currently, with a similar caseload, but with Omicron rather than Delta, we have just 14 people in hospital and one in ICU, she said. This may reflect Omicron's more mild symptoms, but also higher vaccination rates.
"However, we were able to essentially stamp out Delta. With Omicron, we won't be able to do that and we're still in the very early stages of the outbreak. So we must use every day to continue our preparations as Government, as communities and as individuals."
The gap between second doses and boosters was cut to three months last week and so far 57 percent of those due to receive their booster have done so.
Despite New Zealand tracking well, Ardern said it is important not to be complacent.
"We know that the determining factor will continue to be booster uptake. We have had boosters taken up by our population before an outbreak whereas many other countries, they have had it alongside an outbreak, so we are in an unknown period."
Prof Plank said on Tuesday that it is "hard to overstate how effective vaccines are in blunting the health impacts of COVID-19".
"The only reason we can even contemplate outbreaks totalling hundreds of thousands of cases now is that we have high vaccination rates, drastically reducing the risk of hospitalisation and death.
"For most people, if you’re up to date with your vaccinations, the risk of getting severely ill with Omicron is very low. But Omicron still has the potential to overwhelm healthcare systems because of the sheer number of cases it can cause in a short space of time. This modelling shows that the key to avoiding this is boosters."
Dr Audrey Lustig, another of the modellers, said that even with scenarios with high booster uptakes and moderate public health measures - like those at red - "demand on hospitals and intensive care units remains high and would put significant strain on our hospital capacity".
In her Prime Minister's Statement earlier on Tuesday, Ardern said "hospitals have been planning and preparing to provide support to a much larger number of patients".
"Improving hospital treatments are already reducing the likelihood of people needing ICU care. The Government will continue to provide promising new therapeutic treatments."
She said pressure on the health system this coming winter will be reduced through an enhanced influenza immunisation programme and other Government initiatives like extending sick leave.
