The 45 new community cases have called into question the effectiveness of Auckland's lockdown, with the COVID-19 Response Minister admitting there were "undoubtedly" rule-breakers among them.
But Chris Hipkins told The AM Show on Thursday "apportioning blame" is not the way to go, because the Government needs Aucklanders on its side and the outbreak could go downhill if "we get into the blame game".
"There will undoubtedly be some people who haven't followed the rules in this. I don't have a detailed breakdown of exactly who's in that situation, but yes, there have been instances of that where that has resulted in people spreading COVID-19.
"I don't want to overstate the rule-breaking. Ultimately, the case investigation is about ring-fencing and isolating risk rather than apportioning blame and that's absolutely where we need it to be focused on at the moment.
"It's not about hurting people's feelings - it's about getting people to continue to cooperate. If they stop cooperating, then things get a lot worse, very quickly, and ultimately, none of us can afford to have that happen."
The Government will decide on Monday if Auckland is ready to shift down from alert level 3, but with new cases still popping up in double digits, experts say it's too soon.
"I always say 'don't read too much into one day's numbers', but it's those 12 unlinked cases that are quite alarming," Te Pūnaha Matatini disease modeller Shaun Hendy told The AM Show in an interview before Hipkins.
University of Auckland epidemiologist Rod Jackson, appearing on The AM Show with Dr Hendy, said Auckland needs to stay at level 3 until vaccination rates increase, with just 48 percent of the city fully vaccinated.
"We're staying in level 3," Jackson said. "Auckland's not getting out of level 3. Auckland's gonna be in level 3 until we don't have mystery cases."
Hipkins said it's too soon to say.
"The reality is the Government hasn't made the decisions on that yet. What we see in our case investigations over the coming days in terms of, not just the number of cases, but the nature of cases - that will have a bearing on the overall decisions that we take next week.
"But we do want to be able to give Aucklanders back more freedom as soon as we're able to do that so I think that kind of speculation is a bit premature."
Hipkins said he won't "put hard and fast numbers" on how many mystery cases would be acceptable for Auckland to shift down to level 2.
"I don't have a number. We've never put those kinds of hard and fast rules around this. You deal with every decision that you have to take based on the best information you have at the time.
"A lot of people have opinions. The reality, though, is that when the situation changes, they can change their opinions. When you're making decisions, you don't have that luxury. Once you've made the decisions you're stuck with it. So, we typically hold that decision-making until the last possible point so that we've got the best information available to us.
"A mystery case, while it might be called a mystery case, we often do sometimes know some things about that - are they genomically linked to the currency cluster? Is there a potentially likely link even if it's not a confirmed link? What's the geographical area and were they at any locations of interest?
"These are all things that help to paint a bit of a picture. Some mystery cases, yes, they might not be household contacts or close contacts, but there can sometimes be a plausible explanation for how they came into contact with COVID-19.
"One the other hand, if they're popping up somewhere where we don't have other cases, then those are the sorts of cases that are of more concern to us."
Hipkins wouldn't rule out using level 4 again.
"You never say never about anything when you're dealing with this. But what I can say is that level 4 and level 3 restrictions are a pretty big hammer in our fight against COVID but we do have other tools in the toolkit and we'll certainly look to deploy those to maximum effect where we can."
He also pushed back on Jackson's suggestion of a bipartisan press conference with the leaders of each party to encourage people from across the political spectrum to get vaccinated.
"Lovely and symbolic though that may be, that's not going to reach the group of people that we know we are really needing to reach for first doses. They are people under the age of 35, they are not people watching the 6 o'clock news, they're not reading the newspaper."