The world has a genuine shot at wiping out Covid-19, a group of leading health experts say - and a virus-free, transtasman "green zone" could show countries how to start.
Eradication of Covid-19 - that's elimination on a global scale - is seen as doubtful by many scientists, with a widespread view the virus behind it will become endemic.
Last year, World Health Organisation (WHO) officials described eradication as "very unlikely", pointing to the threat of super-spreader events and small outbreaks that could fast become large ones.
Dr Lee Hampton, of global vaccine alliance Gavi, has pointed out that humanity had only ever eradicated one human infectious disease comparable to Covid-19 in its broad geographic distribution: smallpox.
"Even if eradication of Covid-19 is ultimately technically feasible, it will likely be extremely challenging," Hampton argued in a 2020 op-ed.
"A strong, well-resourced effort with effective global co-operation would likely be needed for years before the disease was eradicated."
In a recent interview with US magazine The Scientist, University of Liverpool researcher Kate Baker said she expected the world would "end up tolerating a certain level of disease".
"I don't think that anyone who is reasonably well-informed about infectious diseases and how they move in populations thinks we are going to eradicate Covid."
However, Otago University researchers Nick Wilson, Michael Baker, Louise Delany, Matt Boyd and Osman Mansoor have set out why they think eradication could actually be possible.
In a new blog post, they pointed to two major advances the pandemic had thrown up.
That was the proven ability of prevention measures like lockdowns to check a respiratory virus - even when half of its spread came from those without symptoms - and an unprecedented global effort which quickly produced effective vaccines.
"Together, these two advances suggest that elimination of the pandemic virus could occur stepwise, from countries to regions, making global elimination theoretically possible," the researchers said.
They pointed out that strong public health measures had already rendered 20 per cent of the world's population to live in virus-free areas - China, Taiwan, Vietnam, Australia and New Zealand among them - and said vaccine roll-outs could build on these successes.
Ultimate eradication of the disease offered "huge" public health benefits, they said, sparing hospitalisations, deaths, the lingering impacts of "long Covid", and stopping the emergence of new variants.
The researchers cited estimates suggesting the total cost of delivering vaccines to 92 low and middle-income countries would amount to $2.7b, which could be "easily eclipsed" by the large economic benefits of eradication.
"There is now a window of opportunity with the currently huge political and public interest in Covid-19 to support eradication."
But they also singled out three big barriers: the threat of the virus becoming endemic in animals; failing to vaccinate enough of the world's population; and the emergence of new, vaccine-evading variants.
"Fortunately, however, it may not take long for new mRNA vaccines to be designed and produced against new variants."
In the meantime, the researchers suggested New Zealand could ask WHO to immediately convene an expert review.
Even if the feasibility of eradication was currently uncertain, they said, "progressive elimination" could still offer a way to protect countries' health and economies in the meantime.
"Then if WHO recommends attempting global eradication, New Zealand should, as a high-income country, commit to providing further funds to low-income countries for building primary care services and running Covid-19 vaccination campaigns."
Secondly, they said New Zealand should continue to work to build quarantine-free travel "green zones" with other Covid-free countries such as Australia.
Maintaining a successful travel "green zone" with Australia, they said, would require New Zealand doing more to reduce the risk of border control failures, stemming from infected travellers from "red zone" countries.
"This approach could highlight to the rest of the world how elimination countries can achieve the benefits of international travel – while still retaining their elimination status."
Earlier today, the Herald reported Cabinet ministers will discuss a transtasman travel bubble with Australia on Monday with a view to mid to late April as a potential start date.
Covid-19 Response Minister Chris Hipkins yesterday indicated a bubble would be at least three weeks away because airports and airlines would need time to set up the necessary systems.