Epidemiologist Michael Baker says it's clear the current COVID-19 outbreak isn't under control and it'll be hard to shift Auckland down alert levels next week if there's a pattern of high cases in the coming days.
Forty-five new cases were announced on Wednesday - a significant jump from the eight revealed on Tuesday. Twelve of the new cases are unlinked.
Director-General of Health Dr Ashley Bloomfield says the high number of new infections is to be expected since many are household contacts of existing cases.
The 12 mystery cases are of concern to Professor Baker.
"If you're getting those cases every day, that's a sign that we haven't got control of the outbreak in Auckland at the moment," he tells Newshub.
Among the recent mystery cases is a remand prisoner and another person who turned up at Waitakere Hospital with COVID-19.
"That has always worried me because it means they must be part of a chain of transmission we don't know about," Prof Baker says.
"Every case that you see unexpectedly is potentially the tip of an iceberg."
But COVID-19 Response Minister Chris Hipkins remains defiant.
"We have still got to hold our nerve here. We are still pursuing COVID-19. We are still planning to run this into the ground," he said during Wednesday's update.
Several people in emergency and transitional housing are among the new cases and there are calls for more effort to be put into reaching society's marginalised.
"We've done a lot but it clearly hasn't been enough because we've had four weeks of working very hard to basically stamp out these chains of transmission," Prof Baker says.
He adds that what we're seeing right now are the effects of level 3 where there is more movement and more cases - and that could continue.
"It remains to be seen what the pattern is for the next few days but that's going to tell us what alert level 3 looks like in the current conditions in Auckland."
His colleague Professor Rod Jackson is blunt about the threat of the Delta variant.
"This is the biggest threat to humankind since World War II," he says.
He believes the mechanisms to fight COVID-19 are obvious.
"Everyone is going to either get the virus or get the vaccine. If you get the vaccine it's like a slap in the face, if you get the virus it's like a kick in the head," Prof Jackson says.
In Tauranga, after a positive wastewater test, residents were told to get tested - but the city only saw a slight bump in the numbers. A few hundred extra tests were recorded and officials say more people need to turn up for testing.
"Look with this wastewater detection, it means that we could have COVID undetected in our community, so it's really important that if anyone does have symptoms that could be COVID that they get out and get tested," says Neil Dewet, medical officer of health at Toi Te Ora.
But at this point, it's Auckland that cuts a lonely figure in New Zealand's Delta dilemma. And vaccines and testing are the only way the city just might be able to unshackle itself from what seems like endless restrictions.