On Wednesday Victoria premier Daniel Andrews announced that elimination had drifted beyond the state's grasp, following 120 new cases - up from 76 the day before.
But the number of cases that were infectious in the community went from 40 to 100.
The spread is now so great that elimination is no longer viable, which means plan B. This is basically the same as plan A but with a different goal: to dampen spread of the virus, rather than stamp it out.
The lockdown in Victoria will now remain - a few tweaks aside - until 70 per cent of eligible people have had at least one vaccine dose.
Victoria's pivot from elimination to suppression is what NSW did weeks ago.
NSW has had more than 7500 cases in the past week. On Wednesday there were 917 Covid patients in hospital, including 150 in ICU.
On Thursday NSW had 1288 cases - a new daily high - and the death toll from the outbreak climbed to 107 tragic losses.
After four weeks in lockdown, Victoria is now bracing for more hospital patients and fatalities. On Wednesday there were 37 patients in hospital, 21 in ICU, and two deaths.
The hospital numbers are not too dissimilar to New Zealand, where case numbers hit 736 on Thursday - with 42 people in hospital and six in ICU.
Melbourne-based epidemiologist Professor Tony Blakely says New Zealand has about a 50/50 chance of stamping out the current Delta outbreak. Photo / Supplied
'50/50' shot of eliminating
Melbourne-based Kiwi epidemiologist Professor Tony Blakely gives New Zealand a 50/50 chance of stamping out Delta.
There are similarities with Victoria, he says, with cases in New Zealand typically among people with denser social connections - including young people and multi-generation households - as well as people who are essential workers.
The two key numbers to watch are the cases that were infectious in the community, and the mystery cases.
The former are the pathways where the outbreak can continue to grow despite the lockdown, while the latter would indicate undetected links in the chain of transmission who might also be out and about.
"For all of the mystery cases you've got now, if you don't find out where they got it from, you're going to be getting more people infectious in the community," says Blakely.
"So unless those mystery cases go down towards zero, you're not going to win."
So how are we placed?
New Zealand is nowhere near raising the white flag as Victoria has done.
Wastewater results in Victoria that cannot be explained by known cases are absent in New Zealand so far.
The number of new locations of interest here continues to diminish, suggesting most of the new cases have been in isolation.
Kiwis also aren't suffering the kind of lockdown fatigue that has plagued Victorians, who have spent 220 days in lockdown since the pandemic began.
Protests in New Zealand have been small and quickly broken up by police, compared to the boisterous and crowded affairs in Melbourne.
Director-general of health Ashley Bloomfield continues to stress the importance of staying home for contacts or people who have been to locations of interest. Photo / Mark Mitchell
Prime Minister Jacinda Ardern says the lockdown is working, and there is data that backs her up, including an R0 value under 1.
On Thursday there were 65 unlinked cases, but director-general of health Ashley Bloomfield expects this number to decline as more extensive interviews take place.
At last count - on Tuesday - there were 107 essential workers who had tested positive, but only four workplaces where the virus has spread.
On Wednesday there were 75 new cases, most of them contacts of known cases, and 45 per cent of them from day 12 tests; 27 were infectious in the community.
By Thursday this had dropped to 49 new cases, seven of them infectious in the community.
But there remain many unknowns, including the 7000-odd contacts still to be formally contacted, and - as Ardern points out - the contacts we still don't know about.
This uncertainty is why Ardern and Bloomfield continue to stress the importance of staying at home if you're a contact, or have been to a location of interest.
It's also why asymptomatic testing for essential workers - particularly those who travel in and out of Auckland - is being introduced.
What if we fail?
Elimination isn't necessarily the end-game, but it's the best game-plan for now, and has broad public and political support while vaccination coverage increases.
If it doesn't work, the Government could decide to try alert level 4.5.
That could mean fewer essential workers for Auckland, and tighter enforcement of masks and distancing in the workplace.
But our level 4 lockdown is already one of the strictest in the world, made even stricter recently with mandatory record-keeping and more mask-wearing.
The other option would be following Victoria in conceding that elimination is no longer viable because Delta has spread too far and wide.
This wouldn't even be a choice, but an acceptance that our days of Covid-free bliss are over.
We would still need to be in lockdown to minimise the impact, but hospitals - which are already stretched in Auckland - would be overrun, and the months-long stretch of no Covid fatalities would likely end.
We would suffer, as NSW and Victoria are suffering; Blakely estimates that Victoria will hit 2000 cases a day by the time vaccination rates hit a threshold that would start to flatten the curve.
Ideally we would vaccinate as well as eliminate. Delta can be stamped out - as has happened in South Australia and Queensland - if lockdown is imposed quickly and is followed.
The Government did the former.
It's up to all of us to follow through with the latter.
