The lifting of Auckland's border will not lead to a sudden surge in Covid-19 cases but some will pop up across the country, the director general of health says.
Modelling carried out by Professor Shaun Hendy and his team for the Government shows a worst-case scenario of 16,000 weekly cases.
Dr Ashley Bloomfield said Aotearoa is not on track to hit those numbers.
He told Morning Report he has not seen a model showing exactly when the outbreak will reach its peak.
"Modelling shows you what might happen in the future so it doesn't predict what will happen... The worst case scenario is predicting 16,000 cases in January but that's not what our current trajectory is and that is not what we are anticipating will happen."
He said vaccination rates remain the top priority. At the start of the Delta outbreak in Auckland the rates were around 23 per cent fully vaccinated and are now 90 per cent and are climbing around the country.
Three months in, the modelling projected the number of cases in Auckland would be fewer than 200 cases a day on average over seven days, peaking at 200 per day at the end of November which the city was still on track to have.
The R point value is 1.2 which it has been for some weeks, he said.
"The key point is that even once that boundary lifts, especially with the requirement on people to be either vaccinated or tested, we're not going to see that sudden surge from 200 to 1000 or more cases overnight.
"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."
Asked where deaths and serious illnesses will be most likely to occur, he said unvaccinated people are the most at risk.
Māori and those in remote rural areas were at the top of the list and there were ongoing efforts to lift their vaccination rates.
"This is really critical to preventing hospitalisations and deaths. We have seen the benefit of that in Auckland."
Three months into the outbreak just over 80 people are in hospital in Auckland, and six are in intensive care. Both figures had levelled off in recent weeks.
"We're not going to get to a point where we are going to let the hospital system get overwhelmed. There are actions we can take..."
The 90 per cent vaccination target has not been abandoned. The traffic light system provides a protection framework that offers greater protection to the unvaccinated than the current alert level 2.
The red light greatly restricts people's ability to go into settings where the virus spreads easily, he said.
In Europe, where it is winter, measures are being re-introduced in some countries.
"The advantage we have over Europe is that we're going into summer, not winter, and that's hugely important."
Other data he had seen showed that Aucklanders over summer headed mainly to Northland, Waikato and the Coromandel and efforts are being made to bulk up testing and tracing in those areas.
Bloomfield defended the current contact tracing system, saying it would be able to handle any surge in case numbers.
There is no problem with contact tracing now and the Ministry of Health has more people coming in and more on standby for the summer.
"We have plenty of contact tracing capacity and you can see that that has played a key role in where we have had those cases to date seeding in Northland and other places around the North Island that actually we have been able to shut those down very quickly with the use of contact tracing."
Motorists are being warned to expect hazardous driving conditions.