New Zealand's top doctor admits worst case modelling has COVID-19 cases increasing tenfold this summer to 2000 a day.

On Friday, officials announced 198 new community cases of the virus.

The Delta outbreak is still centred on Auckland, with 152 cases, but it now spans 10 of the country's 20 regional health districts.

Another case has been confirmed in Christchurch, while a weak positive case is being re-tested in Wellington.

There is good news in falling hospitalisation rates, down to 76 after a peak of 93, including six in intensive care, below modelled predictions.

However, Delta is plainly on the march in Aotearoa, as confirmed by the director general of health, Ashley Bloomfield.

Dr Bloomfield confirmed to Radio NZ the reproductive or R value was unchanged at 1.2, which suggests doubling of case numbers roughly each fortnight.

Counteracting that growth is improved vaccination rates, with 82 per cent of Kiwis aged 12 and over now fully vaccinated, and a further nine per cent with one dose.

Health minister Andrew Little told the NZ Herald the reopening of the Auckland border - scheduled for December 15 - would see numbers rise.

"As it moves through the country, there'll be outbreaks, numbers will spike in one area but not in another, and then it'll reduce but spike somewhere else, or it might spike in multiple places," Mr Little said.

The worst-case modelling is 16,000 cases a week, with an optimistic projection of around 250 each day.

Dr Bloomfield said the worst-case scenario was "not what our current trajectory is and that is not what we are anticipating will happen".

"Yes, we will see seeding of cases around the country which we are seeing now but in that situation our contact tracing and testing is able to respond and get around those cases," he told Radio NZ.

New Zealand has had 38 COVID-related deaths through the entire pandemic, including 10 in the last fortnight.

"Where are our deaths and serious illness likely to occur? They are likely to occur in our unvaccinated population, our adult population," Dr Bloomfield said.

New cases were found in pockets across North Island on Friday, including regions with below-average vaccination rates.

The new Wellington case was picked up in a construction worker from Auckland.

Under current rates, Central Auckland will become the first health region 90 per cent fully vaccinated later on Friday.

In other news, New Zealand has completed a deal with Australia to supply AstraZeneca vaccine.

New Zealand's vaccine rollout has been solely Pfizer to date, but it has added 100,000 AstraZeneca doses to its portfolio.

"These doses are for people who can't have the Pfizer COVID-19 vaccine for medical reasons, and for those who would like an option other than the Pfizer vaccine," COVID-19 Minister Chris Hipkins said.

"Pfizer remains the preferred COVID-19 vaccine for use in New Zealand."