Prime Minister Scott Morrison has released the Doherty Institute's modelling which shows Australia's vaccination targets for the path out of the pandemic.
The modelling is what underpinned the vaccination targets set by National Cabinet for the planned four-phase reopening of the country.
Professor Jodie McVernon from the Doherty Institute explained the data but dismissed the notion of a "magic number" of vaccinations that will leave Australia protected against COVID-19.
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"I think the first thing to make very clear is we've had a lot of discussion of herd immunity thresholds and some magic number where there's a binary cut off and above that life is life as normal and below that we haven't achieved our goal," she said.
"Vaccination coverage is a continuum.
"Every Australian who is immunised helps to protect themselves families and community and that will help reduce transmission."
Professor McVernon said the Institute had examined a number of potential outbreak scenarios in communities with different vaccination levels.
"At 50 and 60 per cent we anticipate rapidly growing outbreaks that would be difficult to control, and would require stringent social measures," she said.
"As we reach 70 and 80 per cent, the need for long, stringent measures across whole states, or across extended areas, we believe, will be substantively reduced."
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Professor McVernon said the modelling also showed a steep decrease in people developing serious symptoms or dying from COVID-19 in communities with higher immunisation rates.
"They're decreased across the board," she said.
"This is an artificial scenario we modelled. We're assuming some models are wrong or some are useful.
"But we are making a strategic case here by looking at the whole population and saying if we can achieve this coverage evenly, this is what we can do.
"Obviously in implementation it will be very important to ensure that jurisdictions, small areas, key sub-populations achieve these high coverage thresholds because while unvaccinated groups remain there is still potential for transmission and outbreaks and severe disease outcomes in groups who are not reached by immunisation."
Strategy would bring forward vaccinations for younger people
Professor McVernon said while the modelling showed the benefits of vaccinating the elderly first, a "strategic shift" for vaccinating younger people was also shown.
"Immunising younger people, reducing transmission, is critical to maximising the gains of a whole population program," she said.
She said the new strategy devised by the Institute recommended bringing forward immunisation of 30- to 39-year-olds to the beginning of September, and people aged 16-29 to early October.
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Professor McVernon said this would help reduce transmission.
However, despite vaccinations being opened to certain groups of children, she said the Institute had not factored that into its modelling.
"By vaccinating parents, you protect children and if you look again at the oldest first and the all-adult strategies, you can see adverse house outcomes in children are dramatically reduced by this strategy as well," she said.
Three key findings from economic analysis
Treasurer Josh Frydenberg said there were three key findings from the economic analysis of the Doherty Institute modelling.
The first was that lockdowns and their costs are "very significant" and cost the national economy $3.2 billion a week if there are stage four restrictions across the country.
The second finding was that the cost of lockdowns come down if governments work to get on top of the virus.
"This is the Prime Minister's point," Mr Frydenberg said.
"Early interventions, short, sharp lockdowns, are the most cost-effective way to handle the virus. Particularly at the current time."
The third key economic takeaway was that the economic cost to the country of managing COVID-19 comes down as vaccination rates increase.
"So there's one very clear message out of the economic modelling, which very much compliments the work of the Doherty Institute," Mr Frydenberg said.
"(It) is that until we get to 70 above vaccination rates, the economic imperative is that governments need to move fast to get on top of those cases.
"If they don't we see lengthier and more severe lockdowns which have a much more significant economic cost."
