New Zealand's level-4 lockdown has been extended nationwide until 11:59pm on Tuesday after confirmation the Covid-19 outbreak has spread to Wellington.
The Government will decide on Monday - based on latest cases and information - whether to reduce levels or extend by region, the Herald understands.
Ardern said at today's 3pm update there was some good news but "there was still a lot we don't know".
Ardern said the time between now and Monday would allow the Government to make a better assessment about whether it had spread to other parts of New Zealand.
Because it was the Delta strain it was still too soon to draw any firm conclusions, because of the number of locations and because the spread of the virus among contacts was unknown.
On top of that the outbreak had spread beyond Auckland. There were hundreds of contacts outside of Auckland, including in the South Island.
The virus could spread to other parts of New Zealand in the coming days.
The New Zealand Herald earlier reported that it understood the 3pm announcement will see the extension of the level-4 lockdown. The nationwide lockdown will be extended to line up with Auckland and Coromandel next Tuesday - and a decision made then to reduce levels or extend by region.
Earlier today it was confirmed the Delta outbreak had ballooned to at least 31 community cases and threatened two of the country's biggest hospitals, with officials warning there would be more cases.
At the 3pm update Director-general of health Ashley Bloomfield went over today's new cases, saying Auckland and Wellington public health teams were conducting interviews to get details on movements and locations of interest would be released as it became available.
So far the majority of close contacts were in Auckland, but some were dispersed across New Zealand.
There were locations of interest linked to the Wellington cases, including restaurants and petrol stations.
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PM's five key messages to NZ
Ardern's message to NZ was to please check locations of interest – if you were there at the time and date get tested.
Anyone with cold and flu symptoms should get a test, she said.
If you're a contact please stay home and isolate, she urged.
"Everyone else should stay at home and stick to their bubble."
"You must wear a mask at dairies and supermarkets - and when you leave your home generally"
Wash your hands and scan in when you visit an essential service, she said.
"Even though we all want to block out the memory of 2020, we have been here before and we know the elimination strategy works."
"Everyone needs to play their part."
Ardern said officials were calculating the number of contacts differently due to Delta being more contagious.
More than 2000 Auckland City Hospital workers had returned negative tests. An infected nurse had worked four shifts there.
Infected Air NZ crew member separate to cluster
Bloomfield said there are 31 current cases and that public health teams are now interviewing those infected in Auckland and Wellington.
The Air NZ cabin crew member who tested positive this week after a routine test was not linked to the 31 Auckland cases, but to three others in MIQ, he said. She was now being treated as border-related case.
Day five testing has been arranged for returnees who were in the Crowne Plaza Auckland on the same floor as the original case linked to the 31 community cases.
As of 2pm, 2363 people had been identified as contacts of this outbreak. This numberc excludes the central Auckland Church of Christ and Avondale College contacts.
"If you were at a location of interest then you should get a test and isolate from others," Bloomfield said.
Cabinet met today to make a decision on whether to extend the three-day level 4 lockdown the country plunged into at midnight on Tuesday.
Ardern said, on Tuesday, it was likely Auckland and the Coromandel, the areas where the first confirmed case had been, would be in level 4 for at least seven days.
Eleven new Covid cases, including three in Wellington, were announced this afternoon in a statement released by the Ministry of Health.
The three in Wellington had recently travelled to Auckland and visited a location of interest there.
The remaining eight were detected in Auckland.
Nineteen cases are now confirmed as part of the Auckland outbreak, with the remaining 12 under investigation to confirm the linkage to the outbreak. Initial assessment shows in most cases there is a plausible link, the statement said.
Of the 11 new community cases reported today, one person is in a family bubble with a case reported yesterday, two are in a family bubbles with a case reported on Wednesday and two of the cases we are reporting today are also in a family bubble together.
The international Air New Zealand crew member, reported yesterday, has now been confirmed as a border-related case, and not linked to the Auckland outbreak, based on the results of whole genome sequencing.
All cases have or are being transferred safely to a managed isolation facility, under strict infection prevention and control procedures, including the use of full PPE.
Testing centres in Auckland had their busiest day ever yesterday, by more than 50 per cent.
More than 24,000 community tests were performed across the city, with more than 8000 at community testing centres and around 16,000 at general practice and urgent care clinics.
The Ministry thanked for their patience at sites while there was high demand and for complying with lockdown restrictions.
The Ministry also thanked testing staff for stepping up again and working at pace at the frontline of the COVID-19 response, in high-stress environments while making personal sacrifices to keep our communities safe.
There are 13 community testing centres available for testing across Auckland today, including seven pop-up community testing centres at Narrow Neck, St Lukes, Wairau Valley, St Johns, Albany, Mângere East, and Pakuranga Heights.
There is additional dedicated testing for Avondale College staff, students and whânau, who are considered to be close contacts.
Additionally, about 2600 swabs have been taken onsite from Auckland City Hospital staff, following news a nurse was at work while potentially infectious, and all have been negative so far.
All community testing centres in Auckland are continuing to operate extended hours and many will remain open until 8pm today.
In Wellington, Covid testing is underway, with a range of sites already in place and are additional testing capacity available if needed.
Pop-up testing sites remain open in Coromandel Township, Thames, and Hamilton.
Yesterday, Waikato DHB's laboratory processed 2,590 tests and all returned a negative result.
Further locations, including in rural areas, are being considered to expand the geographical spread of testing to help determine whether there has been any undetected transmission to date.
Covid-19 was detected in wastewater samples collected on Wednesday from the Waitakere area in Auckland. This follows detection in the sample from Tuesday.
There have been no unexpected detections to report outside the Auckland region.