Auckland's Level 3 lockdown is likely to be extended as new Covid-19 cases not immediately linked to the current cluster continue to crop up, according to data modeler Shaun Hendy.
The lockdown restrictions are currently slated to end at midnight on Wednesday, August 26 with Prime Minister Jacinda Ardern expected to give an update on alert levels on Monday.
"I think progress has been really good, the testing rates have been phenomenal, and that's giving us a lot of confidence that we aren't missing big clusters out there," Mr Hendy told 1 NEWS.
"The contact tracing has been working at pace and it's just keeping on top of this cluster. It's growing, but it's not growing exponentially, so that's good news."
However, Mr Hendy said he believes it's "still a little bit too early" to agree with Ms Ardern's ascertions the cluster has been "circled".
He added that the number of cases has grown in recent days, with some cases being "a little bit harder to connect" to what he called "quite a sprawling" cluster which has "definitely touched many parts of Auckland."
"I think this week will be key - the next few days - to see whether that cluster is under control," he said.
"If we see cases cropping up that we can't immediately connect or easily connect to the main cluster - even though their genomics gives us a clue that it's part of that cluster - if we can't find those connections, that's what's always a concern.
"That means our contact tracing is not staying ahead of it, so these extra cases that are coming up, we really do want to understand the links back to the main cluster."
Mr Hendy said while New Zealand is "still in a risky time," Level 3 restrictions "seem to be working".
But while the country isn't "facing a Melbourne-style outbreak" and numbers have fallen or stayed static, they "haven't gone to zero," so the possibility of an extension of Level 3 restrictions in Auckland should be taken seriously.
"I think at this stage, it would be wise to not assume we'll be coming out of Level 3 this week."
Mr Hendy said New Zealand should have tighter restrictions in place at quarantine facilities to prevent workers being infected with Covid-19 by guests.
It comes after it was revealed on Tuesday that a maintenance worker at Auckland's Rydges Hotel was potentially infected with Covid-19 after using a lift minutes after a guest.
"While we are still seeing cases sort of pop up, and have that little bit of uncertainty about things, then a longer lockdown is probably on the cards."