One year on from the country's longest Covid-19 lockdown, an epidemiologist says further lockdowns cannot be ruled out, instead preparing to do them better.

On August 17, 2021, New Zealand went to alert level 4 because the deadly Delta variant had arrived.

Aucklanders had no idea that day that they would still be in lockdown till December, and that after 18 months of trying to keep Covid-19 out, it would be here to stay.

The city was asked to hold the line so the country could get vaccinated, something critics said should have happened much earlier.

Auckland University epidemiologist Rod Jackson was vocal in urging the country to aim high and vaccinate more than 95 per cent of eligible people.

Reflecting back, he says New Zealanders responded well, with most areas hitting that mark or higher by the measurements at the time.

Much has been learnt about the virus - and how to respond to it - since then, with the highly contagious but less harmful Omicron variant changing everything at the start of this year, he says.

But the danger is not over.

"I think there are a lot of people who think 'oh look, it's getting less severe over time so we're fine' but it's pretty random whether the next variant is going to be less severe or not," he said.

Either way, it would need to be at least as spreadable as Omicron to take over, he said.

An Auckland motorway near the city centre, mid morning on August 19, 2021. By September 7, 2021, the rest of New Zealand had move to level 2, but Auckland stayed in alert level 3 restrictions until 2 December. Photo: RNZ / Robert Smith.

The government has said lockdowns are not part of any future Covid-19 plans, with the traffic light system taking its place.

But Jackson says that may not cut the mustard if the worst happens.

"If we get a new mutation that is more severe, that kills more people, then we've got something huge to worry about," he says.

"If that happens, if people start dropping dead in the street like the original version of Covid, we will have little choice but to lock down."

That was why the country still needed to be prepared for the worst, he said.

As an Auckland GP and co-leader of Te Rōpū Whakakaupapa Urutā, Rawiri McKree-Jansen was at the frontline of the Delta outbreak and lockdown and the vaccine rollout.

Some Māori and Pacific health teams initially struggled to be given the resources they needed, or to be listened to.

The work they were able to do for their communities and the country showed what they were capable of and should be a lasting legacy, says McKree-Jansen.

They were crucial to the vaccine roll out and helped the most vulnerable, especially those isolating.

"The mobilisation was impressive, relentless and co-ordinated," he says.

"Those features are remarkable and give us a great sense of optimism about the contribution that Māori communities and Māori health professionals can make and I hope that is enduring."

When it came to new variants, he said while it was important to be vigilant about what may come next, it was also important to focus on what was happening now.

"Omicron's not done with us yet ... I'm keen that we don't forget the lessons we've learnt from the Delta and Omicron outbreaks - and supporting communities is fundamental to that."

Both Jackson and McKree-Jansen acknowledge the people who have died since the pandemic began, many more since the Omicron outbreak that reached so many people.

But they say they are also grateful that many were protected by the lockdown and the vaccine rollout.

-RNZ/Rowan Quinn.