The Director-General of Health says it's unlikely COVID-19 will ever disappear despite global vaccination efforts underway.
Dr Ashley Bloomfield also warned if some of the new variants of COVID-19 escape from managed isolation and quarantine in New Zealand the impact could be greater than it was last year.
Dr Bloomfield told The AM Show on Wednesday viruses such as SARS-CoV-2, the coronavirus that causes COVID-19, don't tend to dissipate.
"If you think about influenza, which was first recorded in 1172 I think, in Europe - these viruses don't tend to die out. They change over time."
COVID-19 is starting to mutate. One mutation that emerged in the UK and another in South Africa, both said to be more infectious, have been detected in New Zealand's managed isolation (MIQ) facilities.
The UK mutation has forced a national lockdown in England as case numbers and deaths hit record highs. Britain has also fast-tracked its vaccine rollout and expects every adult in its population to be vaccinated by September.
"What we're seeing with these new variants - they tend to become more transmissible and less deadly over time," said Dr Bloomfield. "More transmissible ones are the ones that have got an evolutionary advantage, so that's a reflection of where we are in the pandemic.
"Of course, we are able to develop vaccines for them and that helps us build immunity, as well as the natural immunity that people will get who have been infected - so vaccines are a really big focus for us this year."
New Zealand's first vaccines aren't due to arrive until the first quarter of this year. In the meantime, Dr Bloomfield said border officials were working hard to keep the virus and any mutations out of the community.
"There's always a possibility it could slip through," he explained.
"We've got a huge amount of effort going in at the border to make sure it's as watertight as it can be but it's a big operation.
"It's a big venture - it involves 2000 or 3000 people every day."
Dr Bloomfield said New Zealand's testing programme is also robust. He's confident the virus can be kept out of the community but "all New Zealanders need to play their part".
"It may involve future lockdowns but, of course, that's what we're wanting to avoid," he said. "That's not something we would reach for straight away and it very much depends on the situation. What I would say is, though, with these new variants that are more transmissible, the impact if the virus does get through the border could be greater."
The New Zealand Government has signed agreements with four companies to secure enough vaccine doses for its entire population. While the country awaits the rollout, Dr Bloomfield is urging New Zealanders to take warnings about complacency seriously.
One way Kiwis can do that, he said, is by using the COVID Tracer app.
"We've all been on holiday, we've been out of our usual routines but we're getting back into those now, and now's the time not to be complacent. We've got to be more vigilant than we were last year because the impact of some of these new variants would be greater."
