Genome sequencing overnight has confirmed the Covid-19 case detected in the community yesterday has the Delta variant.
There are also four new cases of Covid-19 in the community linked to the initial case, as the country wakes up to Alert Level 4 restrictions.
One of these new cases is a fully vaccinated nurse from Auckland Hospital.
The four new cases are linked to the case announced yesterday: a man from Auckland's North Shore. Genome sequencing for these cases is underway.
They include a co-worker of the man, and three household contacts of that co-worker. Prime Minister Jacinda Ardern told Breakfast that one of the four new cases works in Auckland Hospital and is fully vaccinated.
The Covid-19 Response Minister Chris Hipkins confirmed on Facebook the health care worker is a nurse.
Those who have worked or shared shifts with the health worker are being tested.
Ardern said it was too early to say what sort of work the health worker was doing, but that the Auckland Hospital "kicked straight into gear" and was already identifying the patients the person had worked with.
"Our hospitals are well-versed in managing these things and moving very quickly."
This brings the total number of active cases in the community to five.
“It demonstrates, at this stage, level 4 is the right place to be,” Ardern said.
On Tuesday, the Ministry of Health said a 58-year-old Aucklander from Devonport tested positive for the virus.
Reflecting on how quickly Delta outbreaks have spun out of control overseas, Ardern on Tuesday stated the country "only gets one chance" to stamp out the virus.
"We have made the decision on the basis that it is better to start high and go down levels rather than to go low, not contain the virus and see it move quickly," Ardern said.
The man became symptomatic on Saturday August 14 while he and his wife were in Coromandel township, and visited his GP yesterday. He and his wife are both isolating.
Ardern said health officials hoped to confirm more information about the source of the Devonport case today.
She said wastewater testing from earlier this week, so far, had not returned any unusual results. More test results are expected within the next 24 hours.
"That tells us that, if we have something, it doesn't appear to be a long-standing outbreak because we haven't had anything in our wastewater testing. That includes the wastewater testing around the North Shore."
Dr Ashley Bloomfield said the couple had travelled to Coromandel on Friday August 13 and returned on Sunday August 15.
The locations and times of interest related to the man are on the Ministry of Health's website .
Bloomfield thanked the man for getting tested as well as being a frequent user of the Covid-19 tracing app.
The man was unvaccinated but had taken steps towards booking his vaccine. Bloomfield said the man had difficulties with the online booking system. His wife was fully vaccinated and has not tested positive for Covid-19 at this point.
Ardern encouraged people to get vaccinated against Covid-19 as soon as they are able to.
"This doesn't demonstrate that the vaccine has failed. The vaccine is to ensure that if people do get Covid-19, they aren't so unwell that they are hospitalised or they die," she said.
"It doesn't stop you from getting Covid, which is why we have continued to reinforce how important it is to keep up all those public health measures so we protect those who may not be vaccinated."
Auckland and the Coromandel will enter a seven-day Alert Level 4 lockdown, while the rest of the country will be in Alert Level 4 for three days.
The lockdown is the first in 169 days since Auckland went into lockdown in March.