The chance of Covid-19 once again being transmitted throughout the community is "very high" and that it is only a matter of time before that happens.
That is more likely to happen through ordinary Kiwis at the border frontline - from airport and Customs workers to hotel staff and even bus drivers.
That is according to University of Otago Medical School epidemiologist Sir David Skegg.
Speaking to Newstalk ZB's Mike Hosking today, Skegg agreed that there was a high chance the country could go back to alert level 2.
"But not next week or next month, I hope. This virus is going to be around for a long time.
"It's only a few months ago everyone was saying it's going to be a short, sharp shock. But, we're talking probably years here," he said.
"Unfortunately, the world is a different place and it's almost inevitable with the possibilities of human error, that sooner or later, we will have incursions of the virus into New Zealand."
He said if international students were coming in and being quarantined at halls of residence, for example, we could expect the virus to arrive "sooner or later".
"We need to ensure that we can detect that really quickly and shut it down - and not end up in a Melbourne-type situation."
Skegg acknowledged many people in New Zealand had become complacent about the deadly virus.
The public needed to remember that right from the start, health officials and Prime Minister Jacinda Ardern herself have always said that Covid-19 would come back and that there would be recurrences of the disease.
"Because we saw the rest of the world in such chaos and we're back to a life of relative normality - and we're just loving that - people kind of imagined that we had conquered this thing.
"Well we haven't. All we've done is kept it out of New Zealand."
He said although the country had a robust system in place - one that included the involvement of police and the military - that system could still break down at some point.
"We've seen the occasional cases of people scarpering from these hotels. But the much more likely possibility is that some of the huge number of staff involved at the border, at the airport, the bus drivers, the hotels.
"Sooner or later someone will get infected there and go back to their family and infect members of their family or their friends - and then we could have a cluster.
"So we do have to be very vigilant."