Australia's Prime Minister Scott Morrison has told Australians they must learn to "live with the virus and not to live in fear of it."

That was his message on Aug 23, and the following day he told breakfast television that unless lockdowns were eased Australia will remain "stuck in a cave forever".

This was a reference to the country's states, especially New South Wales, and Victoria, which are in lockdown as the Delta variant of COVID-19 shows no sign of abating.

With vaccination rates steadily rising, the Australian government wants the states to begin easing restrictions once 70-80 percent of the adult population is vaccinated.

These figures are based on modelling carried out by the respected Melbourne-based Doherty Institute and is the basis of the government's national plan to exit lockdowns and live with the virus.

A new paper released Aug 24, however, has cast some confusion over the government's plan. New modelling now suggests Australia should aim for a 90 percent vaccination rate among all Australians, including children.

Ending lockdowns and other public health restrictions once 80 percent of the adult population is vaccinated could result in 25,000 deaths in total and 270,000 cases of long Covid, warned the paper, 'High vaccination coverage is required before public health measures can be relaxed and Australia's international border fully reopened'.

Dr Zoe Hyde, an epidemiologist and co-author from the University of Western Australia, warned the new modelling – which is yet to be peer-reviewed – showed it was "simply too dangerous to treat COVID-19 like the flu" and that Australia should reach higher vaccination rates before opening up.

Hyde and co-authors Professor Quentin Grafton of the Australian National University and Professor Tom Kompas of the University of Melbourne, both economists, called for a 90 percent vaccination rate among all Australians, including children, and a 95 percent rate for vulnerable populations, including elderly people.

Professor Ivo Muelle, co-division head of the Population Health and Immunity Division at The Walter and Eliza Hall Institute of Medical Research, in Melbourne, said: "Releasing and publicising results that are based on overly simplistic concepts and unrealistic assumptions, at a time when an overstretched and exhausted Australian public needs reassurance that the very significant efforts they are asked to sustain will lead to an eventual positive outcome, is not only unhelpful but is in my opinion irresponsible."

University of Sydney Associate Professor Alexandra Martiniuk, who is also a honorary senior research fellow at the George Institute for Global Health, said Australia needs to review more than one modelling scenario.

"This is a crucial time in the pandemic and Australia must not squander its opportunity, keeping restrictions, while awaiting the population to be covered by vaccination – because the alternative (reopening when vaccination rates are too low) risks a 'let it rip' scenario through the unvaccinated, which may overwhelm health services requiring further lockdowns," Martiniuk said.

Professor Robert Booy, an infectious diseases and vaccine expert with an honorary professorship at the University of Sydney, said: "For most, mathematical modelling feels like a black box, not easily subjected to scrutiny. The Doherty Institute has just released the outcome of complex up-to-date modelling. 

"In Australia, how many competing models do we need? Multiple variables need to be accurately measured or estimated. If just one is wrong, what confidence can be put in the predictions?"

The value of modelling depends on multiple scientific disciplines from epidemiology and psychology to mathematics, history and ethics, in his view. "It is not an easy task," he added.

Professor Bruce Thompson, dean of the School of Health Sciences at Swinburne University of Technology said: "The latest modelling regarding the effects of opening up the community too early, or indeed getting to the point of treating the virus like 'the flu' is very timely if not sobering."

However, he said that it needs to be noted that all theoretical modelling is based on a series of assumptions which drives the model of which the output is a "scenario" of what is likely to occur. "It therefore is used as a guide," Thompson said.

"However, these models are sophisticated, and irrespective of which way you cut it, our future path living alongside the SARS-CoV-2 virus will not be the same as living with the flu. The results from the latest modelling clearly demonstrate the need for significant continued social adaption plus also major increases in our healthcare capacity."

Meanwhile, Australia's trans-Tasman neighbor, New Zealand, aims to defeat the virus rather than live with it. 

New Zealand Prime Minister Jacinda Ardern is telling her people the virus "can be defeated".

Within two days of the Delta strain being detected in the country, Ardern began locking the country down. The country, long a pandemic success story, now faces its biggest hurdle since the health crisis began. 

Over the past two months, New Zealand has looked on as elimination success-stories across the Asia-Pacific region began to battle the Delta variant.

With just 23 percent of New Zealand's adult population fully vaccinated, Delta has the potential to rip through the country. New Zealand's pandemic response has been world-beating in the past. Now, its citizens and those in other countries will be watching to see if it can overcome the latest threat, The Guardian reported on Aug 24.