The Ministry of Health (MOH) has revealed 59 essential workers have tested positive for COVID 19 - nearly a fifth of the current outbreak.
Health experts say that number is crucial to judge the success of New Zealand's lockdown and whether elimination will work.
"What we don't want to see is cases cropping up in large numbers of essential workers or spreading between bubbles or mystery cases popping up," COVID-19 modeller Michael Plank told Newshub Nation.
Essential services can come face to face with the public during lockdown, meaning they are most at risk of spreading the virus. Newshub Nation asked how many of those 59 people had passed the virus to others at work - but MOH couldn't say.
Nor could they answer how many cases have spread between bubbles in alert level 4. Dr Plank says getting that kind of information is crucial.
"We would like to see clear numbers going forward on how many people have been infectious in the community...that is important information that we will need to see."
Aside from vaccines, staying home is our best defence against Delta but unfortunately not everyone is on the level. So police have launched a lockdown crackdown, with 69 people charged for breaches and about 700 issued fines since lockdown began.
Police Commissioner Andrew Coster says it's more than this point in level 4 last year.
"It's higher and the reason for that is we've had a shorter fuse in moving towards enforcement in this lockdown than the previous one. The reason for that is with the Delta variant we can't really have any tolerance for large gatherings."
Compliance is vital to eliminating Delta, which is more than twice as contagious as other variants, but 11 days into lockdown Dr Plank says we're starting to see promising signs.
"We've seen cases creep up over the last couple of days but they haven't shot up dramatically and I think that's a good early sign that we are starting to bend the curve."
According to epidemiologist Michael Baker, elimination is still possible but we need more details - not just how many cases, but who.
"I think the chances are very good [we reach elimination]… We need to know something about those cases. I mean, what proportion of them were just household members of known cases, so they were in quarantine, versus cases in essential workers?"
Those details are regularly reported in Australia and experts say they could be the difference between elimination and continued spread. The stakes could not be higher, with a glance across the Tasman revealing why.
Two months ago, Sydney discovered a single community case of Delta - an unmasked, unvaccinated driver transporting flight crew to MIQ.
Today it's become a health disaster, one case has ballooned to more than 16,000 - with up to 1000 new cases a day. Australia's abandoning elimination and its Prime Minister Scott Morrison claims New Zealand will too.
Professor Quentin Grafton is a COVID-19 modeler at the Australian National University and says this strategy could have an horrific human cost.
"Don't believe that message. Living with the virus means dying with the virus."
He's part of new research published this week that says Australia's plan to reopen could cost tens of thousands of lives.
"If some people think that 70 percent vaccination target is going to give you a free ride, in terms of zero fatalities, or very low numbers, and very low hospitalisations, they're living in a fantasy world," he said.
The research found dropping public health measures once 80 percent of Australia is vaccinated could lead to 25,000 deaths. Grafton says they need 90 percent vaccination of every Australian - from five years old.
"We're suggesting the minimum is 90 percent, including children. That's a decision New Zealanders need to make - what they're prepared to accept."
Similar research in New Zealand, which Baker was a part of, found even 90 percent vaccination could lead to more than 1000 deaths.
"The message is that at a certain point we will have a hard choice to make."
He says we may need to change our elimination strategy in future but the best thing for now is to wait.
"With every passing week, we're seeing advances in terms of our understanding of the pandemic and how to manage it."
But with so many cases in essential services, level 4 could be here to stay.
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