The whole country might get a taste of the so-called traffic light Covid-19 response model in weeks ahead.
But the National Party has today accused Jacinda Ardern of engaging in a "weird charade" of setting vaccination targets and then back-pedalling.
Mandatory vaccination remains a contentious issue.
Ardern told Newsroom vaccine certificates could help in future mitigation strategies, and the traffic light system could be extended nationwide when Auckland moves to it - even if other regions had not yet hit the 90 per cent vaccination target.
The new traffic light system involved three stages, all allowing relatively high rates of freedom compared to level three or level four lockdowns.
But the new system was expected to require vaccine certificates for nearly everything apart from essential retail and services, such as supermarkets and GPs.
And after numerous pleas to accelerate integration of low-risk returnees and reduce Covid-19 home isolation risks, Ardern said a new MIQ model could feature as part of a smorgasbord of health measures.
At least three people have died in home isolation and Auckland Airport's chief executive Adrian Littlewood has said MIQ should be ditched for vaccinated returnees.
"Now we're looking at how do we make that transition away from a highly-managed MIQ environment to somewhere where we can still have confidence it's playing a role at home," Ardern told Newsroom.
But she said domestic Covid-19 mitigation measures would have to be maintained, especially if 20,000 or more people were arriving from overseas each week.
Opposition leader Judith Collins suggested Ardern was engaging in chicanery while waiting for vaccine certificates to be prepared.
"The Prime Minister has admitted this morning that the whole country may go into the traffic light system at the end of November, which begs the question as to why the 90 per cent target for every DHB was launched only two weeks ago," Collins said.
"Was it just a play for time to get something as simple as vaccine certificates ready?"
Collins said the 90 per cent district health board target was needed because New Zealand couldn't move to the traffic light system previously.
She said that was because the Government needed another month to prepare vaccine certificates and legislation.
"Instead, we have this weird charade of the Government setting a target and then just a few weeks later walking it back."