Health officials are making immediate moves to try to reduce the risk of an outbreak at the hospital.
The Prime Minister's office has confirmed there are four new cases, all linked to the original Auckland case. It includes a fully vaccinated nurse from Auckland City Hospital.
The Prime Minister's office has also confirmed it is the Delta strain of the virus.
An email sent to Auckland District Health Board staff says a staff member has tested positive for Covid-19.
The emails says the DHB is concerned about a "hospital outbreak" and it is taking "a number of precautions".
"We will be carrying out a detailed contact trace over the next day but in the meantime if you have been in Ward 65 in the last five days please contact Occupational Health and get a Covid test."
The email asks staff to stay home if they have Covid symptoms and get tested. Staff are asked to wear masks at all times in clinical and non-clinical areas and be careful about hand hygiene.
"Please restrict your movements around the hospital. Ideally please go straight to your workplace and stay there. If you can work from home please do so."
The DHB is reducing the number of coffee and food outlets and removing seating in public spaces. Staff are asked to bring food from home to reduce hospital movements.
"The situation is likely to evolve over the next few days. We will provide frequent updates so you can understand what's happening and what it means for you."
The email is signed by Dr Mike Shepherd, interim director provider services.
Meanwhile, the Government is expected to reveal new rules for mandatory mask use today. Masks are currently compulsory on public transport, flights, taxis and in closed spaces where physical distancing is not possible.
Test results due
Test results expected earlier this morning will be critical in determining how the 58-year-old Devonport man got Covid-19 after health officials were unable to identify any obvious links to the border.
Auckland and Coromandel have gone into level 4 lockdown for seven days – and the rest of the country for three days – following a community Covid-19 case in New Zealand's biggest city.
It is the first full lockdown in more than a year, and has seen a "return of the bubble", limited travel, a 48-hour amnesty for people to return to their homes, and a 48-hour pause on vaccinations.
The Devonport man returned a positive test on Tuesday, and is believed to have been infectious since August 12. He and his wife travelled to Coromandel township on Friday and stayed for the weekend, before the man developed symptoms and on Monday sought a test.
There are 23 "exposure events" linked to the man -15 have so far been released as locations of interest - meaning they require further contact tracing. These locations include 12 in the Coromandel, 2 in Auckland and 1 in Mangatarata.
His wife had been fully vaccinated and returned a negative test. The man himself was eligible to be vaccinated, but had issues booking an appointment through the online system.
Both had been self-isolating at home but were being transferred to Jet Park quarantine facility.
Every case of Covid-19 picked up at the border over the past three weeks had been Delta.
New Zealand had seen what had occurred around the world in outbreaks of this new variant, which was twice as infectious and led to higher rates of hospitalisations and deaths, particularly across the Tasman in New South Wales, Ardern said.
Delta was a "game-changer" and there needed to be a rapid response to stop the spread.
"We only get one chance. One of the worst things about Covid-19 is the absolute uncertainty it creates, but we know this strategy works, and we know life will get easier. We just need to keep going."
The three-day nationwide lockdown was to get various test results, identify contacts and the spread, and find any undetected cases. Auckland and Coromandel would most likely be in lockdown for seven days due to the proximity of the case, Ardern said.
Level 4 means schools and all education centres will be closed. Non-essential workers need to stay home, and everybody needs to keep to their "bubbles".
People should only leave their homes to buy essential items, and for exercise in their immediate neighbourhoods.
Masks were not mandatory, but Ardern said people were strongly encouraged to wear them at all times outside their bubbles and maintain at least a two-metre distance with others.
Delta could be spread, as in Sydney, by people simply passing each other in the street.
An announcement on mandatory mask measures was expected within 24 hours, Ardern said.
There would be a 48-hour period during which people could return to their homes, she said.
For up to 48 hours vaccinations would also be paused. This was to prepare the sites to be able to carry them out safely, Ardern said.
There were 23 locations of interest identified - 13 in the Coromandel Peninsula and 10 in Auckland.
The Government has not released the number of contacts, of which there are potentially hundreds.
About 70-80 people alone were in Star and Garter Bar in Coromandel township on each night the man visited over the weekend - including to watch the All Blacks game on Saturday.
Manager Mariya Kravchenko said the hotel closed just before 6pm yesterday, saying staff had been told the follow the guidelines and get a Covid test.
National Party leader Judith Collins said she supported the quick move to lockdown given the transmissibility of the Delta variant.
"It is better to act now to stamp out the spread of Covid-19 than to take half measures which do not work and result in it taking longer to shut down the spread."
Both Collins and Act leader David Seymour said it was crucial vaccinations began again as soon as possible, given the low level of coverage in New Zealand and the harm Delta had done in countries with even fairly high levels of vaccination.
Auckland Mayor Phil Goff said the Government had made the right decision but understood it would be hard on the community and businesses.
"To successfully contain the spread of the virus everyone has to play their part and follow the rules.
"We have a collective responsibility to each other, and it is unacceptable for anyone out of selfish reasons to put themselves, their families and their communities at risk."
Council facilities such as libraries, leisure centres and pools, the museum, zoo, halls, playgrounds and public toilets would be closed.
Auckland Transport would continue its core services for essential workers, but passengers needed to socially distance and wear masks.
Other essential council services would continue.
Finance Minister Grant Robertson said a week-long level 4 lockdown had been estimated to cost the economy $1.4 billion.
The wage subsidy support had been triggered given the lockdown would last seven days. Businesses that met the criteria could apply from Friday.
The resurgence support scheme was also available.
Following news of the lockdown, the New Zealand Nurses Organisation (NZNO) called off a planned strike over pay and conditions for Thursday, saying people's health and wellbeing had to "remain our number one priority".
