Experts say a move to level 2 for Auckland next week is still looking "very risky" despite a drop in new and unlinked cases.
Regardless of any changes decided at Cabinet on Monday, Prime Minister Jacinda Ardern today said the removal of the boundary around the region will not be up for consideration.
University of Auckland associate professor of public health Dr Collin Tukuitonga said he was optimistic cases would continue to decline through next week, but "not get to zero in a hurry".
LISTEN LIVE TO NEWSTALK ZB
Given the nature of the current clusters spreading through transitional housing, which included people living in "very difficult situations" and were often less trusting of authorities and willing to engage and get tested, the tail of the outbreak threatened to "get very long", he said.
"That is why we really need a targeted approach, engaging people from those communities that people trust."
There were 19 new cases announced on Thursday, down from 45 the day before but still a vast increase from the days prior.
Eighteen of the cases were in Auckland and the other is a child who attended Mangatangi School, who had been isolating. The school was at the centre of an outbreak earlier this month after children of a gang member freed on parole became infected.
Sixteen were known contacts, and director-general of health Dr Ashley Bloomfield said they were expecting another 30 cases in the coming days, as 19 of the newer cases were linked to emergency or transitional housing.
Bloomfield said the transitional housing sub-clusters were a mix of hostels, motels and houses - and there was often movement between those places.
There are now seven suburbs of interest. On how the outbreak was evolving, Bloomfield said there were initially four clusters that were active.
There were now several subclusters: two newly identified subclusters were a southeastern Auckland household's subclusters, and a West Auckland subcluster of households. Bloomfield said the new cases were coming from those two subclusters.
Bloomfield urged people from all suburbs of interest to get tested, regardless of whether they were symptomatic or not.
Despite a number of mystery cases circulating, consideration was still being given to whether that alert level would change, and that decision would be made by Cabinet on Monday, Ardern said.
However, she said she wanted to provide some certainty that the boundary restrictions would remain in place, even if that happened.
"We want to get to a position when we can have movement again," she said.
"It causes a huge amount of work for managing the boundary safely and also a huge amount of stress and anxiety for those who are separated.
"Of course, we want to get that movement back, but it needs to be safe."
This would mean the border would remain up through the school holidays, which start next week.
When asked if the border would remain in place until vaccine rates had climbed above 90 per cent, Ardern said that was not a "connection" being made by the Government.
However, high vaccine rates were the key to lifting all restrictions, she said.
University of Auckland emeritus professor of medicine Des Gorman said such a border restriction could be "there for a while", and could eventually see a situation where people needed to be vaccinated and return a negative test to pass through.
"I think our contact tracing and our testing capacity has been so poor and our hospitals are so unprepared and the Government will always take a very low-risk approach."