Prime Minister Jacinda Ardern has vowed to leave "no stone unturned" in the hunt for the source of the Valentine's Day Covid-19 outbreak.
Ardern says officials are "making good progress" in the investigation but work is still under way and the current alert levels will remain in place.
She said the first doses of Covid-19 vaccine arrived on New Zealand's shores today.
Ardern and director general of health Dr Ashley Bloomfield this afternoon gave an update on the three Valentine's Day cases, all of which are within one family.
Officials are keeping an open mind as to which of the three - a mother, father and daughter - caught the virus first.
Vaccine has arrived
Ardern confirmed the first batch of the Pfizer vaccine arrived in the country about 9.30am on a flight - the first batch is 60,000 doses or 30,000 courses.
She said vaccines would continue to arrive in small batches.
The doses will now undergo quality assurance testing and everything is still on track for frontline border workers to start being vaccinated from Saturday.
Ardern wanted to remind New Zealanders the Government had ordered enough for everyone.
"We are very pleased to have reached a milestone today."
The Government had already prepared a scenario that the vaccines would arrive from today.
"We are on track to start [inoculating frontline workers] on Saturday," said Bloomfield.
"It's an encouraging start," said Bloomfield about the fact there had been no new community cases announced today - but the key would be the test results from the community and school which will be processed tomorrow.
The UK variant that the family have is "highly transmissible and a fast-moving chain" which requires fast action, said Ardern. It still has not been linked to a known case in MIQ.
Ardern said officials were going back through the health order mandating testing as to whether it needed to include people in the woman's situation where they had secondary contact with the virus.
When asked whether an earlier vaccine rollout could have prevented this outbreak, Ardern said the vaccine timeline was already earlier than the initial expectation and even if we started some weeks ago frontline workers wouldn't yet be fully protected as the Pfizer vaccines require two doses.
The vaccines will be available for every single person in New Zealand - whether they have visas or not.
"When we say the vaccine is available for everyone - it is for everyone ... as long as you are here with your feet on this soil we want you to be vaccinated," the PM said.
Bloomfield and Ardern said they were both willing to get the vaccines early to overcome vaccine hesitancy but they had to decide whether to move themselves ahead in the queue if it would encourage others.
Ardern said she thought Bloomfield would be a good example of someone who would help instil confidence in the community about the vaccines.
Next few days 'crucial'
Bloomfield said the days ahead would be crucial as the test results from the community surveillance in Auckland and Taranaki come through.
Serology testing has come back negative which confirms all three are active cases.
Testing and serology are happening on "Case B" - the mother - and there is "significant testing" happening at Papatoetoe High School.
There are 42 close contacts outside of the household, including some teachers and students - none have yet returned positive test results and the rest are still being processed.
Bloomfield said there had been a "good response" to testing in Auckland and Taranaki and repeated it was important only the "right people" were being tested.
Ardern urged anyone who wasn't symptomatic or had not been at a location of interest to not get tested in order that those who needed it could be.
Bloomfield said health officials relied on people prioritising themselves when coming forward.
The level changes will help stamp out any chains of transmission, said Bloomfield, and he thanked Kiwis and businesses for adhering to them.
Preparation for the vaccine roll-out is underway, including dry runs and establishing vaccination sites.
A number of vaccinators have completed the two-hour training module to administer the Pfizer vaccine.
Bloomfield reminded Kiwis the Pfizer vaccine was two doses about three weeks apart and it was important to get both.
"Covid-19 can feel like a roller-coaster that you haven't actually bought a ticket for," said Bloomfield.
Saliva testing questions
On saliva testing, Ardern said there were questions about how reliable it was.
New Zealand is at a point where it has no room for false negatives, said Ardern.
The challenge is that New Zealand has so few cases it was hard to collect good data on saliva testing, said Bloomfield.
No cases have been picked up as a result of saliva testing in MIQ - outside of routine testing the positive cases have been detected after the onset of symptoms.
Ardern said "all of us want a wider set of tests" but called the negative close contact test results "heartening".
Ardern said there seemed to be an attempt to build a case to the Government's opposition to saliva testing. "There isn't one," she said.
The saliva testing regime is voluntary. It started in the Jet Park and is being rolled out across other facilities. Officials are assessing what value it has and what role it would play.
"We're testing it at the moment," said Bloomfield.
Ardern said every decision they made included safety considerations and "to keep people working there", given the inconveniences extra measures had on workers at border facilities.
Level 3 transition
Reports from Auckland suggested the transition to alert level 3 had gone "reasonably well", said Ardern, with fewer people on public transport and out and about.
Ardern said it was her expectation that alert level 3 restrictions were enough to contain such a transmissible strain of the variant.
The best way to protect people against the new variants was to protect them against Covid-19, said Bloomfield.
At 1.30pm today, 6861 workers received travel exemptions and more are being processed, the PM said. There is an average of 35 seconds wait time on the call line.
On Auckland's borders - and grocery shopping
Auckland's "legal border" is exactly the same in the north as it was last time - but this morning there was a checkpoint further north. Police are now moving that checkpoint.
Ardern suspected police extended Auckland's border to Mangawhai because it might have meant people could travel more widely in the region but what it actually meant was more towns and communities were affected than needed - but said she wasn't looking to find blame.
Ardern said there was something about human behaviour which led to people panic-buying toilet paper and flour.
"I cannot explain that."
She reminded Kiwis supermarkets will remain open.
No community cases today
There were no new confirmed cases in the community at 1pm today.
At the weekend, after the three people tested positive for Covid-19, Auckland was plunged back into alert level 3 and the rest of the country moved to alert level 2.
The family have been moved to the Auckland quarantine facility while a fourth member of the household has tested negative and is isolating at home.
The level change is in place for 72 hours while officials attempt to find the chain of transmission - and any other possible chains of transmission in the community.
Genomic testing results last night confirmed the family, from South Auckland, was infected with the highly infectious UK variant.
It was not linked to any current or former returnee in MIQ.
One of the working theories is that the mother caught it at her workplace - LSG Sky Chefs - where she handles laundry from international flights.
The woman and her colleagues were tested regularly because of their work but were all tested again in light of the outbreak.
Anyone connected to Papatoetoe High School - where the daughter goes to school - is being asked to stay home and isolate until they get information from the school.