On Wednesday, health officials reported 60 community cases, down from Tuesday's 94 which was the country's highest daily number of the pandemic.

Modellers advising the government believe the "R" value - or how many people each individual case infects - is around 1.25, which will see a doubling of cases each fortnight.

NZ has avoided the worst of the pandemic, with 28 deaths compared to Australia's 1577.

However, a significantly less resourced health system - including half of the intensive care beds than Australia, per capita - means NZ could endure poor health outcomes should cases increase.

"We're likely to see case numbers continue to increase for a period and we do need to be prepared for that," Mr Hipkins told Radio NZ.

"The modellers have different views on where we are likely to top out. It could be as low as 200 or it could be higher than that ... up into the high hundreds."

Prime Minister Jacinda Ardern refused to be drawn on modelling, saying her focus was preventing larger numbers.

"Cases will continue to increase. What we want though is for our ability to maintain a manageable situation," she said.

There are 43 Kiwis in hospital, with five in intensive care.

Contact tracers have their work cut out for them with 180 cases remaining unlinked from the past fortnight.

While Auckland and much of the Waikato is in lockdown, the government is urging vaccination as the key defence of Kiwis.

As of Tuesday, 3.59 million Kiwis are at least partially vaccinated - or 83 per cent of the eligible (aged 12 and over) population.

Two-thirds, or 2.84 million, are fully vaccinated.

"We have to find the unvaccinated people before COVID-19 does," Mr Hipkins said.

"COVID is here. It is in New Zealand ... it will find its way across the country at some point and we want to make sure that people have the opportunity to be vaccinated before that happens."

Mr Hipkins, also education minister, announced school in locked down areas will return from next week but only for years 11 to 13.

"Learners in this age group are able to be vaccinated ... that will allow those students back to school so that they can prepare for their end of year exams," he said.

Mr Hipkins said "the picture is a more difficult one" for years 1-10, deferring a call on returning to classrooms this year.

"Primary school settings ... will quickly become the highest concentration settings of people who are not vaccinated," he said.

Australian Associated Press