Prime Minister Jacinda Ardern says the Red traffic light setting is in place to protect vulnerable Kiwis as Omicron spreads in the community.
"We're a team and some of our team are immune compromised, some of them have illnesses, some have vulnerabilities and of course, some are older," Ardern said.
She says Omicron will affect individuals differently, "If one of us doesn't play our part, then someone else may suffer."
The whole of New Zealand will move to the Red setting of the traffic light system at 11:59pm on Sunday night.
The Prime Minister and Director-General of Health Dr Ashley Bloomfield confirmed in a media conference the nine cases in Nelson and Tasman are the Omicron variant.
Ardern also revealed details of the staged approach that would be rolled out in the wake of Omicron.
The first stage remains the 'stamp-it-out' approach. This period represents where there are only up to 1000 cases a day. The current contact tracing and isolation measures would remain and rapid antigen testing would begin to be integrated.
The second was named the 'transition stage', where there was a "much more" severe risk of Omicron.
The third was where the cases were in the thousands per day. Changes would be made to contact tracing, isolation requirements and changes to contact definition. Ardern said this stage would likely not be for at least a few weeks.
She acknowledged having Covid in the community and the number of cases would be “deeply concerning” for people to hear.