Prime Minister Jacinda Ardern's office has been sent some heavily critical feedback on the Government's draft traffic light system, which is meant to replace alert levels when the population is highly vaccinated.

"Not fit for purpose" and "no consultation" were strong sentiments among the expert feedback for a new system that Ardern will reveal next week.

During a visit to Taranaki yesterday, she said the new system was about incorporating vaccination certificates into a framework of restrictions based on risk.

"How can we use vaccination as a way to give greater access to some of the things that have been high risk in the past?

"There has been consultation on it over the last couple of weeks."

That included a Zoom meeting on Thursday co-chaired by Professor Dame Juliet Gerrard, chief science adviser to the Prime Minister, and Professor Ian Town, chief science adviser at the Ministry of Health.

It included dozens of health experts including microbiologist Dr Siouxsie Wiles, developmental paediatrician Dr Jin Russell, GP Rawiri Jansen, Auckland University Associate Professor Collin Tukuitonga, Covid-19 modeller Professor Shaun Hendy, and epidemiologists Sir David Skegg, Professor Michael Baker, and Dr Rod Jackson.

Hugely grateful to all experts who joined this kōrero - co-chaired by @IanTown3 - this afternoon, but especially those from PHUs at the COVID front line. Goal was to gather feedback on evolving strategy for the PM. A summary will be up on the PMCSA website this month. Ka pai. pic.twitter.com/OvZHqy20nV

— NZ ChiefSciAdvisor (@ChiefSciAdvisor) October 14, 2021

The traffic light system aligns the level of risk to red, amber and green.

In the draft proposal, green is similar to level 1 settings but with mandatory vaccination requirements for large events - which Ardern has already said will be needed for summer festivals.

Amber is similar to level 2, where the virus is increasing in circulation and restrictions such as mandatory mask-wearing would be used. There would also potentially be a requirement for vaccinations at retail and hospitality businesses.

Ardern has said the Government is yet to decide on whether to make vaccinations mandatory for the hospitality sector.

Red is similar to level 2.5, with some limits on gatherings and possibly further vaccination requirements for businesses.

Several people familiar with the Zoom call told the Weekend Herald that the general feedback was that the new system wasn't fit for purpose, and its usefulness was for a time when enough of the population was fully vaccinated - which could be months away.

That is considered to be the only scenario when lockdown restrictions, which were notably absent in the red settings, would no longer be needed.

It would then be premature to reveal it to the public if it wasn't going to be implemented for some time, the Weekend Herald was told, and if it was going to come into force sooner, then that would be risky.

Concerns were also raised around how flexible the system would be, and why it would be better to move to a system than was less nuanced that the current one, and which was also already well understood.

There were also questions around who had developed it.

Level 3 and 4 settings were mooted as still being a necessary part of the toolbox, given the possibility that a new variant might emerge that was resistant to vaccines.

The latest data shows 83 per cent of the eligible population across the country with a single dose, and 62 per cent fully vaccinated (and for Māori, 41 per cent) - well below what those figures need to be to safely jettison lockdown restrictions.

Ardern has previously talked about the ability to avoid level 3 restrictions if 90-plus per cent of the population were fully vaccinated.

The Government is understood to have sought independent expert advice on the public health strategies that should be pursued for a highly vaccinated population.

Cabinet will discuss the traffic light system on Monday, including when the right time would be to transition to the new system, and what the triggers would be to move between the different settings.

The new threshold for lockdown-type restrictions will also be discussed, given the increasingly vaccinated population.

Gerrard, who posted a photo of the Zoom meeting on Twitter, said that minutes for the meeting would be publicly available within a month.