Data compiled by Newshub shows the trajectory of hospitalisations is going up - and we could see up to 200 people in hospital with COVID-19 in the next two months.
Experts say we could follow Melbourne's path, or worse, as our vaccination rates are lower and we have fewer ICU beds.
The head of the Intensive Care Society has a message - get vaccinated or more people will die.
At Dunedin Hospital on Thursday, junior staff were being trained in intensive care medicine, learning how to use specialist equipment like ventilators which help to save lives. They may need those skills soon.
Craig Carr, New Zealand chairman of the Australia and NZ Intensive Care Society, says the danger of our COVID crisis is clear.
"We are watching with bated breath at the moment and very nervously because we're already seeing a slight increase in demand in intensive care services," he said.
"If we are not extraordinarily cautious and careful, we shall see more deaths."
As the COVID-19 outbreak began, hospitalisations rapidly went up peaking at 43 admissions on September 3. They then dropped away as level 4 had an impact.
Then from September 21, as Auckland went to level 3, admissions increased again - hitting 32 on Wednesday, but only 23 on Thursday.
But Professor Michael Plank, from the Canterbury University School of Mathematics and Statistics, says the slight dip doesn't change the outlook.
"On the current rate of case growth, it's quite possible that we could see 100 to 200 hospital beds occupied some time in the next couple of months," he told Newshub.
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New Zealand has 324 staffed ICU beds with an estimated ability to surge to 550. ICU occupancy is currently at 67 percent.
In Victoria, they can surge up to 1000 ICU beds. On Wednesday, the Australian state recorded 1420 new cases. Professor Michael Plank says what's happening in Melbourne could happen in New Zealand.
"It's certainly a real danger and it's very, very serious."
Carr added that the unvaccinated population is "hugely at increased risk of dying".
There are other risk factors like age - Cambridge University analysis shows from the age of 35, the risk of death doubles every seven years.
One graph shows for people over 60, the risk increases significantly.
"So it doesn't take many people in their 70s and 80s and 60s with COVID to need hospitalisation and then intensive care admission to overwhelm the existing healthcare system," Carr told Newshub.
Young, fit people can be affected too. Carr's ICU colleague in the UK died from COVID before vaccines were available. He was a marathon runner in his 40s.
"He's left young children without a dad, so please take this seriously."
If the hospitals are full, doctors may be called on to provide at-home care. The medical director of the Royal NZ College of GPs Bryan Betty says they need to know the Ministry's plan.
"The situation may be quite urgent in terms of how quickly this occurs so again we need clarity as to what that might look like in the community if it was to happen," he said.
The way to avoid health system overload is to get vaccinated - and not just 90 percent - Carr says we need to aim even higher.
Carr wanted to remind New Zealanders that ICUs are busy even without COVID-19, and if hospitals see a lot of people with the virus, elective procedures like knee and hip operations will be deferred, followed by more urgent procedures like cardiac surgery.
The Health Ministry told Newshub it's working on a plan for primary care and public health assisted at home COVID care and will have more to say on the issue "in the coming weeks". It's also looking at giving GPs devices to help measure a person's oxygen levels.
"Equipment including pulse oximeters is being considered as part of the care plan for a COVID-19 patient," a Ministry spokesperson told Newshub.
The Ministry's also working with District Health Boards to develop what it's calling "Community Supported Isolation and Quarantine" to respond to potential community outbreaks.
The community-based programme would help cases and contacts who can't isolate at home.
"Some people may not be able to self-isolate at home because, for example, they live with a vulnerable person or in a large household. Likewise, some people may not be able to support themselves and their families while isolating at home, without assistance," the Ministry’s spokesperson said.