Less than 48 hours 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 said customer numbers had swiftly plummeted after the variant emerged in the community.

It was down about 60-80 percent 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 said.

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

Down the road, Jay Zhang said there were also about 60 percent fewer customers walking through the door at Grain Tea compared to level 1 last year.

He thought a shift back to working from home was to blame.

Today, some Aucklanders and Wellingtonians told RNZ they were relatively relaxed about the outbreak, felt there was "no point stressing" and planned to take it "day by day".

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

People described being uncertain if they should be going to work, and said they were worried about panic buying leaving supermarket shelves empty.

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

He said the Covid-19 Protection Framework did 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 said 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 said.

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 were happy to take it as it comes.

However business owners like Froozanfar were 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 said.

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