Watch - Jacinda Ardern and Ashley Bloomfield LIVE Covid-19 briefing on Omicron / Livestream started at 11am

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The nine cases in Nelson yesterday have been confirmed as the Omicron variant, Ardern said.

Another household member has since tested positive.

They are one family and recently attended a wedding and there is now clear link to the border.

They were on the same flight as an Air New Zealand flight attendant who tested positive.

"That means Omicron is now circulating in Auckland and possibly the Nelson-Marlborough region, if not elsewhere," Ardern said.

Ardern said the focus is on slowing the spread of the Omicron variant and the strategy includes rapid tests, contact tracing and isolating cases and contacts.

New Zealand has system has "significant capacity" to work on stamping out outbreaks due to low case numbers, she said.

"We know we will see far more cases than we have in the two years to date, but the difference to previous outbreaks is we are vaccinated and we are better prepared."

Ardern said it will take a team effort and she's encouraging people to get their booster shots.

Ardern encouraged New Zealanders to get their boosters saying it will help limit the spread and limit the likelihood of someone getting sick or needing to go to hospital.

She also encouraged parents and caregivers to seek out information about vaccines for their children.

Already, 20 percent of children aged 5-11 have been vaccinated or are booked to receive their vaccination.

Ardern is reminding people the red light settings is not a lockdown.

She said it has restrictions, but business is still open, gathering numbers are reduced and differ depending on whether people are vaccinated or not.

Hospitality is seated and requires a single server.

She said schools remain open, with mask wearing for everyone from year 4 upwards.

Ardern said school ventilation systems will be assessed.

Ardern encouraged households to have a "buddy" to help with food, for example, if someone in your household is unwell from Covid-19.

The Ministry of Health yesterday confirmed that another Auckland Airport worker has the Omicron variant of Covid-19. Another Auckland Airport worker was confirmed to have Omicron on 20 January.

An Omicron case was also detected in Palmerston North on Friday and the Health Ministry said it was likely the source of the infection was offshore "rather than transmission in the Christchurch MIQ facility where they stayed".

The government's approach to Omicron has come under flak with microbiologist Siouxsie Wiles warning the red traffic light setting will not be enough to slow the variant down and South Auckland GP Dr Api Talemaitoga saying the government had dropped the ball on rapid antigen tests.

New Zealand has been preparing for the arrival of Omicron in the community with doctors preparing to support people isolating with the virus at home and supermarkets starting to stockpile to meet demand.

The World Health Organisation has said although the Omicron variant appears to lead to fewer hospitalisations than the Delta variant and to be less severe in the elderly and very young, it should not be considered to be mild.

Republished by agreement