Officials are expecting up to 120 cases of delta-strain Covid-19 infections in New Zealand.
Prime Minister Jacinda Ardern and the director general of health Dr Ashley Bloomfield gave today's Covid update at the Beehive.
"We are absolutely anticipating more cases," Ardern said.
Most of the current cases are of people in their 20s and "we could expect already between 50 to 120 cases", Bloomfield said. The key is to find them as soon as possible.
Modelling data showed those numbers were possible, Bloomfield said, and Ardern added that variations will depend on people's compliance.
There are now seven cases in the community, with two more since the five were announced this morning. A 20-year-old and 19-year-old are the latest cases, and are linked to the other cases.
Genome sequencing confirmed the outbreak is the delta strain of the virus, and that it came from NSW.
Among the cases announced this morning are a 25-year-old teacher from Avondale College and a 29-year-old male flatmate.
An infected nurse worked four shifts at Auckland Hospital without knowing she had the virus, Bloomfield said.
Bloomfield said 88 per cent of ADHB staff are vaccinated.
The wife of the first case has returned a second negative test.
Auckland Regional Public Health has identified 16 close contacts of the nurse and 14 have already been contacted.
Four of those contacts are fully vaccinated, three have had one dose and the others are unvaccinated.
Most of the cases identified have been in their 20s and have been "out and about", Bloomfield said.
"We're expecting more [cases] - especially the age group and demographics," Ardern said. Those infected include people who might have visited crowded bars and other "high risk sites".
Ardern said she would look at rates of vaccinations among young adults, because in Australia they have been identified as a "pivot point" for transition. She said it's a matter of days before vaccination will be available for everybody.
NZ has not had a NSW Covid-19 case at Auckland City Hospital, Ardern said.
One was at another hospital - the person was transferred from Jet Park to Middlemore Hospital who travelled from NSW, but the case "doesn't fit with the timeframes" of the current cases, Bloomfield said.
Ardern said Aucklanders who have left their usual place of residence and travelled out of the region should think about how they'd feel if called by a contact tracer.
"Anyone who is breaking the rules, which we very clearly articulate, may potentially put others at risk. It's hard to know where lines of inquiry may end up. People may tend to think, it won't affect me - it may affect you. Just think if you are in the wrong place at the wrong time if you receive a call from the contact tracer," Ardern said.
Church and casino visited
Two major new locations of interest are the Auckland Central Church of Christ, which meets in Freemans Bay, and SkyCity Casino. The church had a service on Sunday, Bloomfield said. The visit to SkyCity Casino was Saturday night, possibly into Sunday morning,
"If you were in either of those locations, look out," Bloomfield said.
Contact tracers are reporting that when they are calling people who have been exposed, they are at home.
"We need you to be at home, not out putting others at risk," said Ardern.
She pointed out that 633 cases were reported in NSW today, many of whom were in the community.
Bloomfield also warned of those who have tested positive in NZ so far: "They have been out and about a lot and I am flagging that there will be large numbers of locations of interest."
Because the Government is focused on getting information out as quick as possible, a business may not be notified before it appears as a location of interest.
Ministry of Education staff have been working with Avondale College, Bloomfield said.
A staff member at Avondale College has been confirmed as having Covid-19, the school confirmed just after 1pm.
"All staff and students of the college are now considered close contacts and must stay in self-isolation at home for 14 days. Even if New Zealand's national alert level changes from the current Level 4, you must still complete your full, 14-day self-isolation."
Healthline calls, testing centre update
Ardern reminded people waiting at testing centres that there was always an initial surge, and there would be wait times. She urged people to still turn up, but take provisions with them.
Bloomfield thanked nursing and midwifery unions for withdrawing strike action scheduled for this week.
There were more than 2000 calls to Healthline overnight.
All testing centres are operating with extended hours until 8pm tonight.
Testing is under way in Thames, Coromandel town, including two pop-up testing sites.
Anyone who is symptomatic or been at a location of interest are urged to get tested.
A close contact of a positive case last travelled to Australia in May, Bloomfield said.
Rosedale wastewater testing results are expected today. Daily testing is taken from the site. Sampling from Whitianga town and other parts of the Coromandel is under way.
Bloomfield said hospitals are open and anyone who needs acute care should seek it. He advised people to ring their GP. Pharmacies are also open under alert level 4.
All DHBs are now required to provide vaccination data. Any staff member who hasn't their vaccination will have an opportunity to do that this afternoon, Bloomfield said.
Genome testing under way
Three positive cases from Sydney went through MIQ in New Zealand in August and genome sequencing is under way on them, the PM said.
The Government will contact all travellers from Australia into New Zealand during the relevant time frame to find whether yesterday's case is linked to them.
Ardern said the Government would leave "no stone unturned" in identifying a case that at some point originated in Australia.
Masks mandatory from tonight
From 11:50pm tonight, it will be mandatory for anyone aged over 12 to wear a mask when visiting essential services that remain open.
It will also be mandatory for staff working at those essential services to wear a mask. Mask wearing is mandatory for bus terminals and in taxis as well.
Police can issue infringements to those who are not wearing a mask under new alert level 4 rules.
Arresting people is theoretically possible, but police don't want to resort to that.
Vaccine programme resumes
There were 55,688 doses of the vaccine given out yesterday - a new daily record for the vaccination programme.
Some vaccination in limited sites will restart this afternoon. The whole programme will resume throughout New Zealand from 8am tomorrow.
Anyone whose booking has been moved will be notified. Otherwise if you're booked for a vaccine in the next three days and you haven't heard anything, please go, Ardern said.
Those aged 40 or over can book online for vaccines from today.
The vaccine means people are "much less likely to get sick or die" from Covid-19, Ardern said. But she said a few still get infected.
Ardern urged everyone to be cautious, no matter their vaccine status.
People who had flights booked but were not flying were urged to cancel them, rather than just not show up.
Police Commissioner Andrew Coster told Ardern that New Zealanders' response to the lockdown is "pretty good".
"So long as we are yet to pinpoint the exact source of this case, I cannot hand on heart tell you the South Island is not implicated," Ardern said, "and that's why it will not be treated any differently."
"That's why we all need to be in it together," she said.
The Government expects employers to use the wage subsidy to pay staff over lockdown, to prevent staff being told to take leave over this time.
Ardern called Cook Islands Prime Minister Brown yesterday and says they are working on their own testing regime. They are happy for people to stay in the Cook Islands, Ardern said, but not happy for more people to enter.
Police respond to protesters
Eight people were arrest and scores of others given a verbal warning after three protests erupted across Auckland, Tauranga and Nelson today.
Four people were arrested after a protest in Auckland CBD. They have been taken into custody and a decision will be made on charges.
"We began arresting people until [the crowd] did disperse," Coster said about Auckland's protest. He said people who gather in that way put everyone at risk.
"It's important not to be distracted by a small number. We will deal with them."
Meanwhile officers arrested four others at an anti-lockdown protest outside the Tauranga Police Station.
Police said they made a number of attempts to engage with around 20 people gathered outside the station but four were taken into custody when they repeatedly refused to comply with restrictions.
Charging decisions have yet to be made.
Around 20 people were issued a verbal warning after protesting outside the Nelson Police Station.
Police Commissioner Andrew Coster said there was significant traffic in and around Auckland last night, before the lockdown, and not all related to people returning home. People appeared to be travelling to holiday destinations.
There's a period of grace before the lockdown starts and it's unfortunate a small group of people chose to flaunt that and do something different, Coster said, about people who attempted to flee to their holiday homes last night.
He said a large number of vehicle were turned around at checkpoints.
Coster said there is no room for crowds to be gathering in context of the delta variant. He said the small number who have is not representative of the rest of the country.
"We know that with delta, the risks are higher, so we've leaned towards enforcement more than we did with the earlier lockdowns, and we will monitor how that's going," Coster said.
4000 of 10,000 frontline police staff are vaccinated. Coster said they are "moving as fast as they can" to vaccinate the rest.
MIQ cases
Three new cases are in managed isolation today, with one day 13 case at Auckland's Pullman Hotel being investigated.
The Ministry of Health says the traveller arrived from Serbia and Montenegro on August 4 and was being investigated as a source of infection.
Two other people arrived in New Zealand on August 13, one from the Philippines and the other from Serbia and Montenegro. Both tested positive on day three.
New Zealanders were plunged into lockdown overnight after a man in the Auckland community tested positive and woke to the news that the Delta variant of the virus has spread from the Devonport resident to at least four others, including a fully vaccinated Auckland City Hospital nurse.
The Ministry of Health will provide an assessment about the extent of likely spread in the community and the length of time the virus may have been circulating in the community.
There is still no link between the five community cases and New Zealand's border or managed isolation and quarantine facilities (MIQ).
The country moved into a snap lockdown last night after it was revealed a 58-year-old Devonport man, described by the Prime Minister as a "tradesperson", tested positive at his local GP.
It was revealed this morning that a co-worker of yesterday's case is also infected with the delta variant.
One of is an Auckland nurse. Auckland City Hospital is preventing unnecessary movements between wards, testing all staff and patients on the ward the health professional worked on. It is also standing down, testing and isolating staff on the same ward.
Locations of interest have been updated today. They are confined to Auckland and the Coromandel Peninsula so far. The Devonport man also visited seven private homes.
New Zealanders are being urged to only leave home if needed, and to wear a mask when they do.
"We know of instances where people have picked up delta simply by walking past someone with it," the ministry said.
Anyone with cold or flu symptoms or who has visited a location of interest is being urged to get tested.