Covid-19 Delta outbreak: Thomas Coughlan - Jacinda Ardern's elimination gamble, as 300,000 people head to work

All Prime Ministers face career-defining decisions where many lives hang in the balance, but the pandemic has forced such decisions on Jacinda Ardern on an almost weekly basis.

But Ardern's decision on Monday to lift alert level 4 restrictions in Auckland at midnight on Tuesday was head and shoulders above the rest for its difficulty and its consequences - it could even be the most consequential decision of her pandemic.

Her decision will mean that roughly the population of Wellington city and Palmerston North combined will return to work on Wednesday, in cramped kitchens and shops throughout the city.

This alert level decision is different. It is the first time part of the country has moved down the alert level scale while active cases of the highly infectious Delta variant were still being discovered in the community.

In fact, daily case numbers are four times higher this time around than they were a year ago when the country moved from level 4 to level 3. Back then, case numbers were in the single digits on the eve of the move.

This time, the rolling seven-day average has hovered above 20 for nearly a fortnight.

And while previous alert level decisions have relied on getting as many test results back as possible, like the recent decision to move Northland from level 4 to level 3, the Government's decision on Monday was made before complete test results were returned from Waikato - an area where there are known cases.

Does the Government know the outbreak is under control? No, it can't - not until those tests are back. Ardern has tried to mitigate this by implementing a "bespoke level 4" - but we know from Australia micro-lockdowns tend to be ineffective.

The political world is buzzing with the question of whether the Government's vaunted elimination strategy is dead. Ardern and director general of health Dr Ashley Bloomfield are adamant the strategy remains in place.

They point to the fact that most of the new cases each day are known infections, many are already in quarantine, and many are household contacts of existing cases.

What's important are the unlinked cases. These cases aren't quite discounted, but they're not considered reason enough for keeping Auckland in lockdown.

In fact, Bloomfield even said on Monday that these cases were treated differently for the calculation of New Zealand's all-important "R" number - the number of people each infected person goes on to infect.

That was news to at least one modeller, who noted no one else seems to treat one case differently to another when calculating R values.

Ardern also ramped up her pleas to people to get vaccinated, urging over-65s, those particularly vulnerable to serious illness and death, to get vaccinated.

Bloomfield said vaccinations were the difference between this and previous iterations of level 3.

"Elimination is about stamp it out, it is about zero tolerance for the virus in our communities - that is what level 3 is about, the difference this time is it is level 3 with high and increasing rates of vaccination," he said.

So there is some hope for elimination - hope that higher rates of vaccination mean the virus can be stamped out in this instance.

But it's a risk.

Epidemiologist Michael Baker suggested to The Project he'd have preferred Cabinet to have opted for more time in level 4, calling the decision a calculated risk. He said alert level 3 could still stamp out the virus - but it would be harder.

For many consumers alert level 3 is justly derided as "level 4 with takeaways", but the fair and justified derision of the Victorian and New South Wales lockdowns has shown it's the details - takeaway shops, retail, construction - that make all the difference.

While white-collar workers may notice little difference come Wednesday, for retail and hospitality, level 3 is vastly different to level 4.

Treasury estimates the amount of economic activity at level 3 is about 10 to 15 per cent below normal levels - that's compared with level 4 which is 25-30 per cent below normal. But that extra activity comes with massive amounts of additional labour.

The Ministry of Business, Innovation and Employment's own estimates suggest about 300,000 additional workers will head to work on Wednesday. They work in retail, hospitality, and construction, sectors that are dominated by young, still largely unvaccinated workforces. Level 3 is a boomer lockdown - vaccinated, wealthy, older people stay home, while everyone else goes to work.

Just 56 of every 1000 people in the 12-19 year age group and 93 per 1000 of the 20-45 year age group are fully vaccinated.

That rises only slightly to the 35-49 year age group of whom 265 of every 1000 are fully vaccinated.

That is not a lot of protection - especially considering vaccination is meant to be the difference between this level 3 and previous ones, according to Bloomfield.

For a young, unvaccinated fast-food worker heading to work on Wednesday, nothing much stands in the way of the most infectious variant of the virus but a verbal commitment from the Beehive that, against all appearances, this is still elimination.

We'll know for sure what it is in a couple of weeks. In many ways, the real test of elimination will come then. If cases begin tracking up again, will Ardern once again plunge Auckland into weeks of level 4 lockdown? Her remarks suggest not.

Or perhaps higher vaccination rates will mean she might not have to make that decision. Either way, the increased risk tolerance Ardern showed on Monday marked a very distinct change in her pandemic response.