Meanwhile Omicron has surpassed Delta as the dominant Covid-19 strain in new daily cases, amid wildly varied modelling about the scale of a looming outbreak.
Yesterday, 34 new Omicron cases were reported out of 45 new nationwide cases, and the Omicron cluster expanded to 90.
Five people in Auckland who attended Waikato's Soundsplash festival last weekend tested positive for Covid-19, with one confirmed as having Omicron.
However a teenager named Emma says out of up to 30 of her group of friends who attended so far 12 have tested positive for Covid.
"I got tested just as like a precaution and then when mine came back positive, I told everyone to get tested," she told RNZ.
"Then everyone got tested and slowly the results have been coming back and it's been one out of every three has been positive."
Emma said some of her friends who tested positive will be going to have a second test.
It is not yet known what variant she and those who have tested positive have got. Emma acknowledged that strict safety Covid measures were followed at the festival.
However, she said members of the public did not appear to "bother" scanning the Covid Tracer app codes located around the site.
"It was pretty strict. My vaccine passes were scanned, we had to be fully vaccinated. All the staff were wearing masks."
Auckland Grammar headmaster Tim O'Connor said the school year had been back for just three days when he made the decision for 120 students at the Soundsplash festival to leave class and get a test as a safeguard.
He told Newstalk ZB's Tim Dower those who had been at the festival were asked to leave the central Auckland campus, get tested and produce a negative result before coming back to class.
"It was pretty likely that it was going to become a location of interest but we couldn't afford to wait until 10.30am when it was announced by the ministry on their website," said O'Connor.
He said they couldn't afford to have 120 boys in class across the school and risk just one being positive and potentially forcing the campus to close just as it had started term one.
Even though the ministry said they should self-monitor for the next 10 days, as a precautionary measure they asked for pupils to return to class after a negative result, he said.
It was important for schools to act swiftly and be conservative in their approach regarding Covid, said O'Connor. And it was far more preferable for students to be absent for two days awaiting test results rather than losing large groups of students off school for weeks.
O'Connor said he was not advised by the Ministry of Health over the situation which affected so many students at his school.
He said he had been watching the official locations of interest website from 6am in order to make an official decision. No mention of Soundsplash came until after 10am.
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The Act party said health officials left people out of the loop, leaving the festival and school to clean up a mess.
"It was up to concerned parents to contact politicians and the media when cases were identified," party leader David Seymour said.
"Now it's been left up to Auckland Grammar to send at-risk students home to isolate after receiving no guidance from the Ministries of Health or Education."
The Epsom school's headmaster, Tim O'Connor, said sending people home was a precautionary step.
He said instead of waiting indefinitely for an official decision on whether attendees would be described as close or casual contacts, the school decided to act.
Soundsplash could turn into a super-spreader event, microbiologist Dr Siouxsie Wiles said earlier.
The Ministry of Health said 68 festival attendees were identified as close contacts, but this number was expected to increase.
At a press conference, Prime Minister Jacinda Ardern did not directly address claims health officials were slow to let Soundsplash organisers know about potential positive cases.
The Institute for Health Metrics and Evaluation (IHME) reportedly projected an Omicron outbreak in New Zealand could last about three months and peak at 80,000 daily infections.
Earlier this week, Health Minister Andrew Little said he was confident the health system could cope, despite predictions daily cases could reach 5000 to 50,000.
Ardern said vast variation existed in current Omicron pandemic modelling.
Addressing media near a Lower Hutt vaccination clinic, the PM said she'd asked experts to meet, compare different models, and reach a more consistent analysis.
Another of Ardern's messages yesterday was delivered away from the spotlight, at Waiwhetu Marae.
"We are trying our best to learn the lessons of the past," she said.
"The next stage is going to be a tough one. But the response from everyone so far has set us apart from everyone else. And I think that's because of our heart."
He said rapid, reliable tests were essential "to keep moving goods around the country, food on the shelves in supermarkets, and medicines in our pharmacies".
National's leader Chis Luxon previously said saliva testing detected Omicron faster than nasal testing, but authorities were in "a nasty spat" with a private testing company.
Seymour also voiced concern about the Government's handling of saliva testing regimes.
"The rationale for testing at the internal border is gone, and that's a good thing."
But he added: "It seems they're just cancelling most of the project and saying: If you want to pay for it, you can."
The Government in recent days has urged people to prepare for possible stints of home isolation if the Omicron variant outbreak grows.
Trade Me yesterday emailed members advising them to shop for "wellness kit essentials" in a list that might elicit angst for some and nostalgia for others.
The online marketplace's list extended beyond face masks and sanitiser to include monitors, exercise gear, trampolines, educational toys - and breadmakers.