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Two more top Auckland schools, Western Springs College and Pukekohe High, and two of New Zealand's best-known companies, Sky City and Sky TV, have been caught up in the Covid Delta outbreak - with positive cases of students and staff.
There are now seven schools caught in the pandemic, with Avondale College, McAuley High School, Northcote College, Lynfield College, and De La Salle College also hit by cases.
Sky TV and Sky City casino are working to identify close contacts after they each had a worker test positive.
The developments come as more than 10,000 close contacts - from Auckland and Coromandel to Wellington and some parts of the South Island - have now been identified in connection with New Zealand's so-far 72 confirmed cases, 66 of whom are in Auckland and six in the Capital.
There are also around 200 visits to 165 locations of interest, including four in three central North Island towns - areas where a Wellington pair had stopped while driving back to the Capital after visiting Auckland.
Prime Minister Jacinda Ardern yesterday warned cases will continue to rise into the next week - and an extension of the Auckland lockdown, at least, seems inevitable.
Te Pūnaha Matatini Covid-19 modeller Professor Shaun Hendy said based on their modelling they were still predicting about 100 cases to have been circulating before lockdown.
All of the cases so far had been linked to the cluster before the lockdown began.
Hendy said he expected numbers to start peaking early this week, but they wouldn't know how effective the lockdown was at containing the spread until next weekend.
"The big unknown is how effective level 4 restrictions are with Delta. We know it worked well last year but this is a more transmissive variant now so we expect the lockdown to be less effective."
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Covid-19 cases associated with the Auckland Delta outbreak are expected to rise into at least early this week with the Prime Minister signalling a lockdown extension for the city "very likely".
Twenty-one new cases of Covid-19 were announced in the community on Sunday bringing the total number of people infected in the latest outbreak to 72.
There are 66 cases in Auckland and six in Wellington. Several more schools in Auckland have been linked to the outbreak and more than 10,000 contacts identified and told to self-isolate and get tested.
Experts say the swift lockdown and likely link to the border should have limited the spread, however due to Delta's increased transmissibility it remained to be seen how effective lockdowns were at containing the virus and this would not be apparent until likely next weekend.
Ardern said she expected cases to rise into early this week before they started to drop.
Because Auckland was at the centre of the outbreak it was "very likely" restrictions would remain beyond Tuesday, Ardern said.
Cabinet was meeting on Monday to decide on any extensions and/or lowering alert levels for other parts of the country.
The virus could continue to spread during lockdown, as had been seen in New South Wales, Ardern said.
Ardern said the 825 cases announced in NSW on Saturday was "devastating".
Te Pūnaha Matatini Covid-19 modeller Professor Shaun Hendy said as had been seen in Sydney, and recently in an Auckland MIQ facility, the Delta variant could be spread by fleeting encounters metres apart.
However, measures like compulsory mask-wearing were in place to counter some of that, Hendy said.
Another major concern was the number of locations of interest popping up with high numbers of people.
New Zealand's biggest university and two more top schools have had students test positive for Covid - sending at least 7000 secondary students and their families into isolation.
A student who later tested positive for Covid-19 attended an Auckland University ball of 500 people. On Friday it was revealed people at two big events at Spark Arena - a Mitre 10 awards ceremony and a Bayleys Realty event - needed to isolate after a bar worker at the venue tested positive. Yesterday, the Bayleys event vanished from the Ministry's list of locations of interest, but a ministry spokesman last night confirmed it would be back on the list tomorrow - people who were there needed to isolate. He said it had unfortunately dropped off the webpage list temporarily.
"Some of those events have potential to be superspreading events, like the awards nights, so it is still possible we could see high numbers of cases.
"If we did see that then there is a chance we could also see spread in the essential workforces remaining open. If there was any transmission there it could push the lockdown out."
Director of Public Health Dr Caroline McElnay said there were 5065 contacts identified by 1pm yesterday, with another 5000 expected by the end of the day.
Hendy said this rate of contact tracing was far higher than had been seen during last year's lockdown, and, provided the case numbers decreased, they should have a handle on the "perimeter" of the outbreak in a few days.
McElnay and Ardern were unable to say on Saturday how many of the current cases were vaccinated.
Given the spread was mostly among younger people, Hendy said it was likely they were less vaccinated which would also see a higher transmission rate.
"Although it is not perfect it does substantially reduce the chances of being infected, and that will be playing a role now and impact how we control things.
"If coverage is up around 70 per cent we might not have to resort to level 4 for Delta outbreaks.
"The other factor that could push up the cases is young people do have considerably more interactions with large groups, socially and also in education settings."
Friday saw a record number of vaccinations - 56,843 - and record number of Covid-19 tests - 41,464.
Ardern lauded the "record numbers" and urged people who needed to be to get tested so they could get on top of the virus spread.
The number of locations of interest has also nearly reached 200. They now include three central North island towns - Bulls, Waiouru and Tokoroa - along with Auckland, Wellington and Coromandel.
With the growing number of cases Ardern confirmed Jet Park Hotel quarantine facility was not at capacity.
She said they were confident they could find places for positive cases if Jet Park reached capacity.
Regarding planning for Delta, Ardern said they had increased ICU capacity in hospitals since last year, and denied they had not adequately prepared for such an outbreak.
"Our goal has always been to do everything we can to prevent it entering at the border. But you still have to have a plan, and we do, that's what we are activating now."