One of the most important ways COVID-19 cases are identified and the spread of Delta is investigated has been sidelined.
Health officials have revealed they're no longer spending time trying to find out how mystery cases became infected, and the focus is instead turning to isolating contacts of mystery cases.
There have been 166 mystery or unlinked cases recorded in the past two weeks.
Director-General of Health Dr Ashley Bloomfield says with the number of unlinked cases continuing to grow, the important thing now is not to try and trace where the link is to the outbreak.
Epidemiologist Professor Michael Baker says that is a real concern and without that deeper level of contact tracing, New Zealand risks losing control of the virus.
"I suspect this is one of the most important parts of contact tracing and it's not a part we'd want to lose," he says.
"Otherwise you will lose control of the outbreak."
There's also been a shift to focusing just on high-risk cases, for example, an essential worker who tests positive. Additionally, ringing casual contacts has been scrapped.
Professor Michael Plank, from the University of Canterbury's Department of Maths and Statistics, is also worried about the sudden shift in contact tracing focus.
"There's a danger that if contact tracing doesn't perform effectively, the rate of case growth, which is already going up, could accelerate further and that things could spiral out of control," he says.
Professor Plank says he'd like to see better use of technology.
"We need to make sure we have some more scalable options like Bluetooth tracing and automatic notifications, and potentially even asking cases to identify contacts themselves and ask them get tested or isolated."
Dr Collin Tukuitonga, who is Associate Dean Pacific at Auckland University and has been supporting Auckland Public Health's contact tracing team, says staff are feeling the pressure.
"I do know there's a lot of exchange about people feeling really, really stretched and stressed and management and team leaders are offering support," he says.
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Official information obtained by Newshub reveals that New Zealand was struggling even at the beginning of this outbreak.
Five days before it started on August 13, Newshub was told Auckland Regional Public Health's response unit was "fully staffed". But a situation report a few days later when the outbreak began, on August 18, revealed the reality - limiting factors included "identifying, attaining and retaining skilled personnel".
On August 19, 14 extra staff from the vaccination programme started to be trained and by August 21, Auckland Public Health "advised teams are at full capacity".
Dr Tukuitonga has sympathy for his public health colleagues who he says work long hours, but it's been too much for some.
"People have resigned and moved on to other things. They just find the roles too stressful," he says.
He says he'd like to see a review of our contact tracing workforce, with a greater focus on roles for Māori and Pacific people.
"We knew this and we could have done this much, much earlier."
But he noted that such a workforce is limited, and every outbreak has complexities because they "rapidly evolve" in a way that often can't be planned for.
Professor Baker agrees that our contact tracing team needs extra support.
"It shouldn't be struggling at just 100 cases a day. It clearly needs more resources put into it."
There have been some contact tracing success stories - recent situation reports obtained by Newshub show how we crushed the rising number of Pacific cases in Auckland by effectively ring-fencing the Mangere church outbreak.
