Covid-19 modelling expert Professor Shaun Hendy says a longer lockdown may be necessary to ensure the latest community outbreak of the virus in Auckland is contained.
On Saturday, a new community case - Case M - was announced. He is a 21-year-old man who visited several locations, including a gym and food outlets.
The new cases in the Auckland outbreak, which stemmed from a family at Papatoetoe High School, are the new, more transmissible UK variant of Covid-19.
After Case M was announced on Saturday, Prime Minister Jacinda Ardern put Auckland back into Alert Level 3 and the rest of the country in Level 2 from 6am yesterday morning. The current restrictions will last for seven days.
"What the modelling says is you want to stop this variant early, that's the unequivocal conclusion from the modelling," Hendy told Breakfast this morning.
"You do not want to let clusters like this grow before you act."
When asked if seven days was too soon to come out of lockdown, Hendy said it was too early to speculate.
"It's hard to say at this stage, we'll learn a whole lot more about the shape of this cluster over the next week," he said.
"We'll need to go through the large volume of testing that we have been doing in Auckland over the last few weeks. We need more testing to be done to tell us about that cluster."
Hendy said there would be more of an indication about how long it would be necessary by mid-week, when potential cases would start to emerge.
"We can think back to earlier in the year and late last year where we had some events, some infections which didn't go on to produce large clusters - that's a possibility here. But it's also possible that we've had a large number of exposures and we might be looking at a larger number of cases, in which case a longer lockdown will be necessary.
"We've got to keep this lockdown in place until we're very sure this cluster is contained."
Auckland microbiologist Dr Siouxsie Wiles also told Breakfast the Government had a "tricky" decision to make about the country's lockdown.
"The question we need to be asking ourselves, and the Government will be asking themselves the same question, is do we do a longer but short, sharp shock and do we do it once? Or do we play whack-a-mole where we come out thinking we're okay but actually there are still some people incubating and then they move out of Level 3 and then we get transmission again?
"So that's the really tricky thing I think we're in now."
However, she said Kiwis needed to play by the rules, amid reports of Aucklanders heading out of the city as the new lockdown was announced.
For those that say it is safer to head away than stay in Auckland, Wiles said it "completely misunderstands the reason why we are at Alert Level 3".
"We should be behaving like we have the virus, you know, it's not about you going somewhere safer, it's about you having potentially being exposed and incubating the virus."
People are allowed to return home, but Wiles urged those people leaving Auckland to take Level 3 restrictions with them.
"I don't want people to be fearful by saying 'think that you have the virus', I want you to have some compassion and think about and be considerate, and think about what your actions might cause," she said.
Watch Dr Siouxsie Wiles and Professor Shaun Hendy's full Breakfast interview below: