* Ten confirmed cases of Delta as of Wednesday night. Public warned there will be more cases: 50–120 people could have been infected prior to lockdown, according to early modelling
* As of Thursday, masks must be worn by customers and staff at supermarkets, pharmacies, petrol stations, as well as at healthcare facilities, in public transport terminals (bus stops, train stations), on flights and in taxis or ride-share cars. Police will enforce the new rules.
* Vaccines rollout re-starts tomorrow morning after a pause to give centres time to move to level 4. PM urges people to get vaccinations, even if booked during lockdown. Over 40s could book from yesterday.
* Outbreak confirmed as the NSW Delta virus. The source remains unknown, there was no link yet to other cases in MIQ. The tests of the only remaining three MIQ cases are expected today.
* A growing number of locations of interest in Auckland and Coromandel for the confirmed cases, including Sky City Casino, several central city bars and restaurants, a church, and several North Shore supermarkets. All Avondale College staff and students told to isolate for 14 days and get tested
Three new Delta cases have been confirmed since 1pm - one of whom has a link to the border - and there are 19 new locations of interest in Auckland including several supermarkets.
An AUT student is among the now 10 confirmed Delta community cases - the student was in a lecture theatre with 84 other students while infectious yesterday.
"[Auckland Regional Public Health] information indicates that the student was at a Social Institutions (SOSC 583) lecture in WG403 at the City Campus between 11.30 and 1pm yesterday (17 August) and was infectious at the time," said AUT vice chancellor Derek McCormack, in an email to staff.
"We have identified there were 84 other people in attendance at the lecture.
"While this is not yet a complete picture, we are working closely with ARPHS and will provide more information as soon as we get it. You will be contacted if you are identified as a close contact and provided with information about isolating and getting tested."
The Ministry of Health said the three new cases this afternoon, who are all in Auckland, were:
- A man in his 20s. This man is the partner of a known case who was reported as a positive case this morning.
- A woman in her 60s. Interviews are underway to determine any link to existing cases. This woman has a connection to the border.
- A woman in her 20s. She has a connection with another case reported today.
And in addition, two cases announced at 1pm today have now been linked to existing cases, the Ministry said.
- A teenage woman who was a close contact of a case reported today.
- A man in his 20s who visited the household where three of the cases reported today reside.
"Movements of all cases reported continue to be investigated. Investigations also continue at Auckland City Hospital, where one of the cases worked for four shifts during their infectious period."
Prime Minister Jacinda Ardern and director general of health Ashley Bloomfield announced at 1pm that there were two further community cases of Covid-19, bringing the total at that time to seven.
Covid-19 Minister Chris Hipkins said on RNZ Checkpoint it was "almost certain" the 58-year-old Devonport man is not the index case connected to the border.
"Almost certain they were given Covid-19 by someone else. What we're trying to do is identify how many steps in that chain of transmission there are before we got to the Devonport case."
Hipkins said there were several ways the Delta strain could have entered the community including through MIQ, someone could have jumped the border by travelling from NSW to another Australian state and then flying back. "We're not ruling anything out."
The number of locations of interest in Auckland has grown by 19, to 21, with a number of North Shore supermarkets and CBD eateries and bars added to the growing list.
AUCKLAND LOCATIONS OF INTEREST
St Pierres Sushi, Elliott St, Tuesday, August 10, 1pm-1.15pm
Avondale College, Thursday, August 12, 8.45am-3.15pm
Glasscorp Limited Albany, 124 Bush Rd, Rosedale, August 12, 12.30 pm-1.00 pm
Unique Hardware Rosedale, 1/16 Arrenway Drive, August 12 12.30 pm-1.00 pm
Avondale College, Friday August 13, 8.45 am-3.15 pm
Crumb Grey Lynn, Ariki St, Thursday, August 12 10am-10.10am
Sweat Shop Brew Kitchen, Sale St, Friday August 13, 2.15 pm-2.30 pm
Denny's CBD, Hobson St, August 13, 1am-1.30am
Bar 101, 18 Elliott St, August 13, 11.33 pm-1.15am
Sky City Casino, Saturday August 14, 1.15 am-3am
Pak N Save Wairau Rd, August 14, 3.20 pm-3.50pm
Central Auckland Church of Christ, 52 Hepburn St, Sunday August15, 10.15am-12.02pm
BP Northcote, 50 Northcote Road, Northcote, Sunday August 15, 7.15 pm-7.30 pm
Devonport Pharmacy, 33 Victoria Rd, Monday August 16, 2.15pm-2.30pm
Green Bay Takeaways, 56B Godley Rod, August 16, 4pm-4.15pm
Passion Bakery, 34 Birkdale Rd, August 16, 12.45pm-1.15 pm
Countdown Birkenhead, Cnr Highbury Pass & Birkenhead Ave, August 16, 12.30 pm-12.45 pm
Warehouse New Lynn, 7/13 Rata St, August 16, 7.45 am- 8.15am
Countdown Birkenhead, Cnr Highbury Pass & Birkenhead Ave, Birkenhead, August 16, 7.00 am-7.15 am
Avondale College, August 16, 8.45am-12.00pm
Remuera Exchange, 2A Dilworth Ave, Tuesday, August 17, 1.33pm-1.35pm
The number of locations of interest in the Coromandel grew by two to 14. The two new locations are:
Driving Creek Railway Tours Coromandel booking office, 380 Driving Creek Rd, Coromandel, Saturday August 14, 10.30am-10.50am
Driving Creek Railway Tours Coromandel train tour, August 14, 11.20am-1.00pm
Meanwhile, a top Covid-19 modeller says New Zealanders should prepare for an outbreak already with a median size of 90 to 100 cases - with the possibility the virus has been quietly spreading for weeks.
Genome sequencing confirmed the outbreak is the Delta strain of the virus, and it originated from New South Wales' major flare-up.
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Bloomfield said most of the current cases were young people, and "we could expect already between 50 to 120 cases".
That range was based on new modelling by a team led by Professor Shaun Hendy, of Te Pūnaha Matatini, who told the Herald the median range was sitting around the 100 mark.
"It could be a bit higher or it could be a bit lower."
Because there was no established link to the border yet, the modelling assumed the virus had been circulating for several weeks.
"But there are a couple of things that are helping us and that bring those estimates down," he said.
"One is that vaccination rates are now at the level that they are starting to make a difference to spread.
"Another is that testing rates have been pretty good.
"And a third is that wastewater testing last week came back negative so far too."
Fellow modeller Professor Michael Plank said in the short term, we could expect numbers to grow.
"It's important to remember that when we detect an outbreak like this, we expect to see a lot of cases come in at the start, because that's our contact tracing catching up with the virus," he said.
"So we shouldn't be too alarmed to see a high rate of cases coming in. But that said, obviously, the more cases we pick up in the outbreak, the worse the situation is."
"If it turns out a close link can be established with a case who has returned from New South Wales via the MIQ system, the outbreak could be at the small end of the scale.
"If the source case travelled to New Zealand from another Australian state not required to go into MIQ, the virus could have been spreading undetected for some time and the outbreak could be much bigger."
Plank said an optimistic scenario would also assume the incursion again hadn't resulted in a "super-spreader" event.
"We would still see more cases in this scenario - but not too many."
A number of locations of interest already identified could host such events: among them, Avondale College, SkyCity Casino and the Auckland Central Church of Christ.
Bloomfield pointed out most of the cases identified were in their 20s and had been "out and about", Bloomfield said.
"We're expecting more [cases] - especially the age group and demographics," Ardern added.
Those infected include people who might have visited crowded bars and other "high-risk sites".
Hendy said a "network" model his team were using was offering slightly lower case numbers than other models.
It brought together an impressive array of data - capturing how many people were likely to live in certain households in certain places, and where they travelled to each day - and was much more sophisticated than models used during last year's main outbreak.
"But the challenge we have with our network model is you have to know where to seed it - so if you find out a case is in Devonport [where Case A lives], it's not going to spread as quickly as one in the CBD," Hendy said.
"So you have to take these results with a grain of salt."
Whatever the case was, Plank said moving the whole of New Zealand to Level 4 "was definitely" the right move and would offer the best chance of stopping the outbreak before it became too large.
"Vaccination will help slow the outbreak, but coverage is still too low to make a big difference," he said.
"Although the case lives in Auckland, the virus could be anywhere in the country.
"The national alert level change buys us some time to see results of testing and contact tracing to assess how widely the outbreak has spread."
Plank said Sydney's experience had already shown that half-measures could lead to disaster.
"It's better to go hard at the start and then relax, than the other way round. With Delta, there are no second chances," he said.
"If we all play our part, there's every reason to think that this outbreak can eventually be crushed."
The danger of Delta
While New Zealand has proven stunningly successful at stamping out past strains of the Sars-CoV-2 coronavirus, the Delta variant has changed the game.
Within months of its detection, the Delta variant has become the main variant in many countries, and what one US public health scientist has called the "greatest threat" of the pandemic in 2021.
Perhaps the biggest risk factor is its ability to spread quickly through populations: it was thought to be partly responsible for India's disastrous second wave this year.
It has been shown to be potentially more than twice as transmissable as the original variants.
While the Alpha or B.1.1.7 variant, which was first detected in Kent, England, was between 43 and 90 per cent more transmissible than earlier variants, Delta could even be between 30 and 100 per cent more transmissible than Alpha.
Although coronavirus outbreaks have tended to follow the "Pareto" or 80-20 principle - in which just 20 per cent of cases cause 80 per cent of infections - studies have suggested Delta flare-ups come with a higher number of infected contacts.
That trend was seen in New Zealand's main outbreak, when one in five adults were responsible for up to 85 per cent of the virus' spread.
In virology, that proportion of people responsible for large amounts of disease transmission is also called the "K number".
Yet the reproduction, or "R0" number – that's the average number of people an infected person passed the virus on to – of the Delta variant has been estimated at five, which is twice as high as the original strain.
So, does a higher "R0" number in turn mean a higher "K" value?
"Delta means that people have an increased viral load, so they're more likely to shed more virus, so I'd assume that the ratio would increase if you had people transmitting to more people," ESR and Otago University virologist Dr Jemma Geoghegan told the Herald last month.
"But it's still hard to know how exactly those ratios change – maybe you've got more of a 50 per cent chance of transmitting. I just don't think there's an answer yet, and I'm not sure if there will be."
Part of the reason could be small changes in the "spike protein" of the variant, which it uses to bind to the ACE2 receptor that gives it entry to human cells.
Another study has suggested a separate mutation could help its ability to fuse with human cells once it latches on – which then allows it to infect more cells and ultimately overwhelm immune defences.
There is also now much evidence to suggest people infected with the variant become more infectious earlier than that of its virus predecessor.
That backs research from Chinese doctors who say up to 12 per cent of patients are becoming severely or critically ill within three to four days of the onset of symptoms.
In the past, the proportion had been only 2 or 3 per cent of those infected.
A study by University of Edinburgh researchers, and published in The Lancet, also suggested the variant carried about double the risk of hospitalisation compared with the Alpha variant.
During the period studied – April 1 to June 6, 2021 – there were 19,543 community cases and 377 hospitalisations where a specific variant of Covid-19 was confirmed.
Of these totals, 7723 cases and 134 hospitalisations were found to have the Delta variant.
And transmission could occur incredibly quickly and easily.
That was demonstrated by the fact the variant was able to be passed on in Auckland's Jet Park quarantine facility last month when room doors in a corridor were opened simultaneously, only for a matter of seconds.
Because of the higher spread rate, experts have warned that, without hard and swift action, our contact tracing capacity could collapse under a Delta outbreak.
That has not been helped by the fact most New Zealanders haven't been using the NZ Covid Tracer app under alert level 1, despite nearly three million downloads to date.
Modelling by Te Pūnaha Matatini researchers has indicated that 83 per cent of Kiwis will need to be vaccinated against less transmissible virus strains, like the original wild type, for measures like lockdowns and 14-day quarantine to be no longer needed.
Yet 97 per cent of the population will need both Pfizer shots to abandon such measures if the country is hit by a wave of a strain as transmissible as Delta.
"If a person infected with a more transmissible variant leaked through New Zealand's border controls, and this sparked a community outbreak, it could be very hard to eliminate," Te Pūnaha Matatini modeller Dr Rachelle Binny told the Herald last month.
At the least, hard social distancing measures like level 4, rapid contact tracing and other measures would likely have to be thrown against an outbreak involving multiple variants, she said.
And even if the virus could be eliminated, it could take much longer on average, and we could expect high numbers of infections before the outbreak was contained.
In this latest instance, that appears to be a worrying possibility.
As Ardern said today: "We are absolutely anticipating more cases."