For the seventh day in a row on Friday, no new cases were reported.
Auckland University professor Shaun Hendy said to now have only one active case of COVID-19 in the country with the possibility of that dropping to zero in a few days is quite an achievement.
But he said no country in the world is sure that they have identified every case and the tricky thing about this disease is that there can be people with almost no symptoms who may still be infectious.
"That's really the risk we're managing at the moment, we're very confident about the cases that we know about, we've managed those well, people have isolated or gone into quarantine in order to prevent the spread to other people."
But he said there is a risk that cases have been missed although the risk is becoming smaller and smaller.
"There's still that chance that there might be that one or two unknown cases out there and as we come back together, as we go through these thresholds, get back into social gatherings, there is the possibility that we'll have another spreading event and we'll see more cases.
"So it's a risk management exercise at this point."
Hendy said the model simulations are showing that New Zealand is very close to having zero cases, but that there could still be a handful of unknown active cases.
Once New Zealand has zero active known cases of the COVID-19 the risk will start to shift to the country's borders and people coming in from overseas, he said.
Hendy said it will be a judgement call as to when the borders can start reopening.
"There are a lot of things in place now to protect us against a further outbreak, there's our contact tracing system, there's our testing regime and then there's the kind of controls we have at the border.
"And when you pull all those things together I guess that's the thing that Cabinet's going to be looking at ... it'll have to be confident that we've got all those things in place, as well as what our modelling is actually saying which is actually we're pretty confident there isn't undetected cases out there."
Hendy said it is important to step through the changes cautiously because now gatherings of up to 100 people are allowed under level 2 that could put a strain on the country's contact tracing resources.
He said it is all a risk management exercise, and it is important to be cautious and go through the various levels as we head back to normal life.