The Government is today forging ahead with plans to open the vaccination programme to an extra 1.5 million people even as it battles to secure enough supplies to keep up with surging demand during the outbreak.
Case numbers declined for the second consecutive day yesterday, though experts warn against complacency with "mystery cases" continuing to linger.
September 1 also marks the day the country south of Auckland moves to alert level 3, while Auckland and Northland remain at level 4.
Prime Minister Jacinda Ardern said the move to level 3 was "progress" but still required "a high level of caution".
Today is also the day the vaccination programme opens to those aged under 30 and over 12, about 1.5m people.
Ardern said the Government could need to slow vaccine rollout to pre-outbreak levels if it cannot secure more supplies - and has not ruled out slowing or halting new bookings in other regions to allow it to keep pace in Auckland.
Ardern said the "surge" prompted by the outbreak had pushed vaccine rates up to 80,000-90,000 a day - and well over 500,000 a week.
The problem is about 800,000 doses are in stock, and deliveries at the moment are averaging about 300,000 a week.
The original rollout plan was to be vaccinating about 350,000 people a week at this point.
The pressure comes off next month, when the country will receive nearly all of the vaccine it hopes to administer by the end of the year - roughly 4 million doses in total - but at current rates could risk running low, or need to slow, this month.
Ardern said yesterday efforts continued to secure more vaccines keep up with that surge demand, and she would be making announcements on these in the coming days.
It is understood efforts include looking at swapping vaccines with other countries further along their rollouts for ours at a later date - similar to deals Australia has done with Poland and Singapore.
Meanwhile, there was an air of optimism from director general of health Dr Ashley Bloomfield on Tuesday as he reported 49 new cases, all in Auckland, a drop from 53 the day prior and peak of 83 on Sunday.
It took the outbreak to 612 cases overall - 597 in Auckland and 15 in Wellington. One new case was a fully vaccinated staff member at Springhill prison.
It was the lowest number of cases reported in six days, and was also accompanied by the positive news 66 per cent of Sunday's cases were household contacts and 77 per cent did not create any new exposure events.
This meant only 23 per cent were considered to have been infectious while in the community.
These cases could have been visiting the supermarket or been an essential worker, Bloomfield said.
This was an improvement from 52 per cent of Sunday's 83 cases being household contacts, and 72 per cent not creating any new exposure events.
It all meant the new cases were increasingly household contacts, or people who had been at a location of interest of a case and would have had to be self-isolating also.
The reproduction rate, "R" number" was remaining under 1, meaning "we are successfully breaking chains of transmission", Bloomfield said.
However, there remained 51 "mystery cases", which had not yet been linked to another case. On Sunday there were 53 "mystery cases".
Bloomfield said sometimes there was simply a lag in identifying the link, and often new cases filled the gap. "Nothing concerning" had been reported by district health boards about these cases, he said.
Epidemiologist Dr Michael Baker said there was reason to be optimistic, but was reluctant to identify a trend just yet.
"The critical thing is being certain about where these mystery cases are coming from."
While they could be cleared up in days, they could also represent "leakage" in the lockdown system and points of community transmission.
Some could be bubble breakers passing it along to many others, or essential workers in tightly controlled environments. There were 106 essential workers infected in the outbreak so far, including three announced Tuesday at the Tegel chicken plant in Henderson, Auckland.
"Household contacts are not so much of a concern but we really want to see those cases still being investigated get down to zero as quickly as possible," Baker said.
There were 34 people in hospital from this Delta outbreak, down three from the day before but another five in ICU at eight, including two on ventilators.
The hospitalisation rate was about double during the major outbreak last year and reflected the severity of Delta, Bloomfield said.
The youngest person in hospital was 18, Bloomfield said.
In the broader outbreak most were under 30, with six under the age of 1.
The Herald has requested figures from the Ministry on vaccination rates and demographics for those in hospital, but had not received these by deadline.
Ardern said despite the move to alert level 3 people needed to remain cautious.
Bubbles remained, but people who were isolated and who needed support could bring another person into their bubble.
Certain businesses could operate as long as they were contactless.
With hospitality businesses, contactless delivery and pick-up could occur but all staff and customers were legally required to wear a mask for outwardly facing businesses such as supermarkets and petrol stations.
It was revealed yesterday a new variant, known as C. 1.2, was detected at the New Zealand border in Auckland in late June. No cases had been identified since.
It was regarded as potentially worse than Delta, and Bloomfield said they were keeping a close eye on it.
"It will be interesting to see if it becomes more transmissible and a more dominant variant, but at the moment it's a variant of interest."