Just days into the red setting, a shift in work habits and daily routines is playing out on central city streets around New Zealand, causing stress for business owners.

A Covid modeller warns although Omicron is moving at sprint speed, the impacts will play out more like a marathon.

In Auckland, Celine Mediterranean Cuisine owner Ebrahim Froozanfar says customer numbers have swiftly plummeted after the variant emerged in the community.

It's down about 60-80 per cent on peak times last year, leaving him very "stressed".

"People are not showing up and I don't know what I should do. And no staff. We have a couple of staff but we don't know when we should tell them to come to work," he says.

"Pretty much, we're reaching the point we should shut down and go home."

Down the road, Jay Zhang says they also had about 60 per cent fewer customers walking through the door at Grain Tea compared to level 1 last year.

He thinks a shift back to working from home is to blame.

Shelves at Countdown, St Lukes, Auckland, were stripped of toilet paper following the announcement that the country would move to red. Photo: RNZ / Kymberlee Fernandes.

Some Aucklanders and Wellingtonians have told RNZ they are relatively relaxed about the outbreak, and feel there is "no point stressing" and plan to take it "day by day".

However, others say Omicron is weighing heavily on their minds, making them feel "nervous, for sure".

People describe being uncertain if they should be going to work, and say they are worried about panic buying leaving supermarket shelves empty.

Te Pūnaha Matatini complex systems researcher Dr Dion O'Neale says individuals and businesses are likely to end up doing more to slow down Omicron's spread than the red setting requires of them.

He says the Covid-19 Protection Framework does not set out clear requirements for businesses in terms of mask-wearing and distancing.

"It's left a lot of that for businesses to interpret in terms of heath and safety legislation. But if we have Omicron in the community it does become a case of - if workplaces want to be operating on site, employers do need to be doing things that ensure their employees do stay safe."

He says the businesses that do, will be the ones that feel less disruption from the outbreak, and it could serve to slow down the total spread of Omicron in the community.

"You might expect things to drag on a little longer. You do still have that spread going through the community and people becoming infected. You haven't put an intense period of pressure on your health system and other supply chain systems," he says.

Various modellers have been pointing to a peak in mid-to-late March, although they say Covid-19 is hard to predict.

Aucklanders and Wellingtonians told RNZ they are happy to take it as it comes.

However, business owners like Froozanfar are eager for a return to normal operations.

"We just need the government to wise up and open the border like everywhere else in the world," he says.

"Everywhere else is doing the business now. The whole world is opening."

-RNZ/Katie Todd.