While falling case numbers are providing hope, New Zealanders are being warned the Delta variant of Covid-19, and how quickly it spreads, means elimination could still fail.
Academics say the reality of losing the elimination fight would be grim.
Restrictions would need to be in place for months until vaccine rates climbed above 80%, the virus would probably escape Auckland, the healthcare system could be overwhelmed and there would be deaths.
The warnings come against the backdrop of Victoria following New South Wales in giving up on elimination and shifting to containment.
University of Otago epidemiologist Prof Michael Baker remained confident New Zealand would eliminate the virus, but acknowledged there was a risk it could fail.
"There has always been a risk that we would fail against the Delta variant."
If the Delta variant spread out of control, it would not mean the end of restrictions. Instead it might mean lockdown, for Auckland at least, could need to be extended until Christmas.
This would be a new reality for New Zealanders who, due to the success of elimination, had lived with the fewest restrictions in the world for the past 18 months,
"I don't think we even fully necessarily grasp what it will be like if we lose control of this virus," he said.
There would be an element of luck in whether New Zealand was successful.
It could depend on messaging getting through to marginalised sections of society who were less engaged in the Covid-19 response.
People in these sections of society were less likely to follow the rules because they might be facing difficulties — for instance poor housing or drug addictions — that meant Covid-19 was not the biggest challenge in their lives.
If Covid-19 spread into these communities it would be hard to contain, Prof Baker said.
"It’s not the middle-class who we have to convince — the jogger who doesn’t wear a mask or something. I don't think that is where we are going to win or lose this."
University of Canterbury mathematical modeller Prof Michael Plank said there was still a good chance elimination would be successful, as it had been with Delta outbreaks in South Australia and Queensland.
But success was by no means guaranteed.
"There is a chance that elimination will be unsuccessful because the Delta variant is so infectious and spreads so quickly.
"But even if we can't eliminate it, giving it our best shot will put us in the best possible position going forward by keeping case numbers low and buying time to get more people vaccinated," Prof Plank said.
If New Zealand moved from elimination to containment the situation would be "incredibly tough".
"The outbreak would inevitably spread from Auckland to the rest of the country. This would lead to hospitalisations and deaths, and we would all be living with strict restrictions and lockdowns for most of the rest of the year."
Removing restrictions would mean the situation would get out of control quickly, Prof Plank said.
"Our models show that, if restrictions were loosened significantly, cases would grow very quickly and, at our current levels of vaccine coverage, could overwhelm our hospitals within weeks."
Melbourne epidemiologist Prof Tony Blakely, who still holds a position at Otago University, told RNZ there was a significant risk New Zealand would be forced to follow Victoria’s lead and shift to containing the virus.
"You need to keep going really hard for another week or two, to see if you can get those numbers turned and going down, but you may have to consider this pivot as well."
Prof Blakely said in Melbourne and Sydney the virus had spread out of control in suburbs with high numbers of multi-generational households, people with English as a second language, and with casual and essential workers.
"And when I cast my eye across to New Zealand that is pretty much what South Auckland looks like, too.
"So I do hope New Zealand is successful with the current lockdown in getting rid of the virus one last time, but it's pretty tough."
Asked if the Government was working on a back-up strategy for if elimination failed, Covid-19 Response Minister Chris Hipkins said: “New Zealand remains fully focused on its elimination strategy."
"All efforts to date, including contact tracing more than 35,000 people and ensuring they are tested and isolated, back this strategy.
"We are confident we can beat Delta and return to the freedoms New Zealanders have grown used to. "
