The Government needs to urgently look at imposing a level 4 lockdown in Auckland to contain the ever-increasing rise in Covid cases.
And if they don't, people can expect to hear of cases rising up to 150 cases a day by as early as November, Covid-19 modeller Professor Michael Plank says.
Plank's comments come as Deputy Prime Minister Grant Robertson announced 71 new cases of Covid-19, all in Auckland.
There were no cases elsewhere, however, traces of Covid have been found in wastewater in Te Awamutu and Raglan.
Robertson was quizzed on Thursday about imposing a short, sharp lockdown but he said it wasn't something they were currently looking at.
The outbreak could still be controlled at alert level 3, however it was no longer just a couple of clusters, it was affecting all of Auckland, he said.
The reproduction rate was now around 1.2 and 1.3 which meant cases would rise and if cases did head towards the "triple-digit mark" he assured they could be managed.
Dr Caroline McElnay of the Ministry of Health said there would be a doubling of daily cases in the next 14 days based on current modelling if the current trend continued.
Robertson added that home isolation was now being actively considered by the Government.
Plank said with cases likely to hit 150 in just over two weeks, that would mean roughly 100 hospital admissions a week which in turn would put immense pressure on the country's hospitals.
"It's clear that the cases are starting to rise more steeply and on the current trajectory we could easily look at 150 cases a day by early November and that could be putting 100 people in hospital each week.
"If we want to prevent that from happening we do need to act relatively soon because there is a significant lag between taking action with something like an alert level change and that filtering into hospitalisations."
Plank said people getting infected wouldn't likely turn up for another seven to 14 days.
"So once you're on that increasingly steep trajectory it can take a while to turn around.
"They need to be seriously thinking about it now."
However, it would depend on variables including the load on the contact tracing system because if it started to keep up with the demand it could exacerbate the number of cases and load on hospitals happening even sooner.
"So, we may be very near to that point.
"We're moving now to put people into home isolation, which is inevitable, and we don't have the MIQ capacity to put that number of cases in."
Home MIQ did come with "greater risks".
"Particularly, those people in large households and multi-generational households so there's a danger this change will accelerate things.
"There are a bunch of tipping points which is difficult to say where they are but it's fair to say we're not far off some of them."
Asked whether the spike in cases was the result of moving down alert levels, Plank said it was "at least in part" as it was hard to pin it down to a single cause.
"I think the move to alert level 3 has increased the rate of cases that we're getting."
At the time, Plank labelled Auckland's move down to level 3 a "calculated risk".
"It's about to look like it was a risky move," he said.