Prominent microbiologist Siouxsie Wiles is "really worried" about the government's plan for an Omicron outbreak, warning the red traffic light setting will not be enough to slow the variant down.
Prime Minister Jacinda Ardern on Thursday announced all of New Zealand would move to red within 24 to 48 hours of Omicron transmission being detected in the community.
Ardern ruled out using regional boundaries or lockdowns.
Dr Siouxsie Wiles - from the University of Auckland - told RNZ the traffic light regime would be less effective at managing Omicron given the variant's infectiousness.
"I'm really worried that the measures we have in place for red are just not good enough at stopping transmission."
Wiles said in the case of an outbreak, authorities should immediately shut down certain venues and activities.
"Certain kinds of activities are just really high risk: indoor dining, night clubs. Regardless of whether you can stay one metre away from other people... those are still high risk situations.
"If we can stop people spreading the virus, then we can stop Omicron. And the more we do to stop transmission, the quicker it will be over."
Ardern yesterday said Omicron's infectiousness would make it "nigh on impossible" to eliminate, but that the red traffic light setting would help slow it down.
Under red conditions, public facilities and retail can operate with capacity limits. If using the vaccine pass system, restaurants and cafes can serve up to 100 people. If not, they can serve takeaways only. Gatherings are capped at 100, for vaccinated, or 25, for unvaccinated.
The prime minister promised to release more details next week about how Omicron cases would be managed on the basis it was "a less severe illness" for most people.
Wiles pushed back against any "damaging messaging" implying the Omicron variant was not dangerous.
"We still don't know the long term consequences of this," she said. "What are we going to be finding in the future? We should not want to catch this!"
People needed to mentally prepare themselves for "massive numbers of cases" and start thinking about how best to keep themselves safe, Wiles said.
That meant getting booster shots, securing effective masks, like N95s, and wearing masks correctly in indoor environments.
Wiles said vulnerable people should also consider limiting their own interactions through self-imposed lockdowns, but that was not an ideal outcome.
"One of the really unfortunate things is that the privileged people will be able to change their behaviour," Wiles said.
"Those who still have to go to work in risky environments will bear the brunt of the infection."