Prime Minister Jacinda Ardern says Auckland will stay in Covid-19 alert level 4 for another week, until 11.59pm next Tuesday.
Cabinet has made an in principle decision that Tāmaki Makaurau will then move to alert level 3.
The rest of New Zealand will remain in alert level 2 until Tuesday next week.
Alert level settings will be reviewed next Monday.
Ardern says while there is nothing to indicate there is Covid-19 outside of Auckland, the lower restrictions there mean a far greater risk of spread if it did escape.
Having the rest of the country at alert level 2 means a greater chance of stamping the virus out if it does get out of Auckland, she says.
Auckland has been at alert level 4 since midnight on 17 August after an outbreak of the Delta variant of Covid-19.
Cabinet has seen evidence and advice that alert level 4 is working, saying it has consistently reduced the R value below 1, and it is now about 0.6, she says.
"On that basis and on the advice of the Director-General of Health, Auckland will remain at alert level 4 until 11.59pm next Tuesday, the 21st of September."
Director-General of Health Dr Ashley Bloomfield says the "lockdown is working" and it's really only a small number of cases that the ministry is focused on.
"The testing is at a good level ... so our view and our advice is that another week in lockdown in alert level 4 in Auckland gives us our best chance to really finish the job off here."
He says the focus for the next week is finding cases.
Cases, testing and vaccination
Ardern says today there are 33 new community cases to report, but only one of them is currently unlinked.
"Likewise of the cases reported yesterday, just one remains unlinked to the wider outbreak at this point."
Ardern says in some cases where an epidemiological link has not been able to be built, the genome sequencing is still able to tell authorities how the case fits into the outbreak.
They expect to have more information about the one as-yet unlinked case reported today.
Ardern says one reason for the bigger numbers over the weekend is high rates of transmission within households.
Bloomfield says mentioned yesterday, about 16 percent of very close contacts become cases.
"That in and of itself will generate about another 50 cases in the coming days and we're starting to see some of those come through."
The number of unlinked cases goes up and down every day, Bloomfield says.
At 9am there were 17 unlinked cases but only a small number of those the ministry was really worried about.
Ardern says surveillance testing of healthcare workers and essential workers has also not identified any transmission.
"It's also clear there is not widespread transmission of the virus in Auckland."
Ardern says there are two key features of recent cases that are of interest. She says there are three clusters that still have cases emerging, and there is the ongoing emergence of cases that are initially unlinked.
"Mystery cases are still coming through, and the fact that we are finding them through surveillance and community testing rather than through contact tracing, that is what we're concerned about because that does present risk."
She says there are seven suburbs of interest where people should remain especially vigilant for symptoms. They are: Mt Eden, Massey, Māngere, Favona, Papatoetoe, Ōtara and Manurewa.
She says one of the points the health team has made is that they are more concerned about some unlinked cases than others.
"There's really only three or four that we discuss in a lot of detail because there's not really an early hint of what's happened."
The cases that are still of concern include one case in Mt Eden, and cases that have arrived into Middlemore.
She says additional testing is brought in to support in places where such cases arise until an epidemiological link is found."
That leaves two very clear tasks - active cluster management and surveillance and community testing, Ardern says.
The third ask is to get tested for even mild symptoms. "Please don't put it down to winter chills, we know that right now there isn't much of that going around. Flu traffic in particular is showing us that."
She says the government wants as many Aucklanders as possible to have had their first dose by the end of the week. She says people booked for October should consider going online again and seeing if more bookings have opened up.
Another option is going to a drive-through vaccination clinic, with no need for booking.
Bloomfield says we are vaccinating at a great rate and it is important to get to the highest rate possible. He says it is also no good if there are pockets within the community who are not vaccinated, so they are also focusing on vaccinations in smaller communities.
They are also looking more closely at vaccinations for children aged five to 11, he says.
Ardern says there is also more financial support for businesses available than was during the last lockdown.
This includes ongoing wage subsidy and resurgence payments.
Message to Aucklanders
"To all Aucklanders, you've done an amazing job so far protecting yourselves, your family and your community," Ardern says.
"We owe you a huge debt of gratitude ... but the cases are telling us we have additional work to do."
She says four weeks into lockdown, it might be tempting to relax their bubble, but asks everyone to treat every day as seriously as they did day one.
People should have an assigned person who goes to the supermarket, Ardern says.