"By vaccinating parents, you protect children," Doherty Institute director of epidemiology Jodie McVernon told reporters on Tuesday.

Professor McVernon identified young adults as peak transmitters, but said the modelling showed vaccinating children is "not an efficient strategy" at this stage of the pandemic.

The research commissioned by the federal government is based on patterns from the past 18 months of coronavirus in an Australian population aged 16 and above.

The full technical report released on Tuesday included some work on targeting 12 to 15-year-olds, but showed the reduction of transmission would be close to zero.

"I am a parent, I was a paediatrician before I was a public health doctor," Professor McVernon said.

"Children are very important. So a strategy that protects them as well as elders in the population and the working-age people we believe to be the best strategy at this time."

Prime Minister Scott Morrison acknowledged public health tools have been blunted by the more virulent Delta strain.

He said the virus would continue to evolve, and work on the best response "will never stop".

Infectious diseases physician and mathematician Emma McBryde said the immediate priority should be 18 to 30-year-olds, but warned teenagers could become a reservoir of infection.

"I think we need to look at where the infections are happening, and at the moment in Queensland it is in high school kids. So we seriously have to look at vaccinating children," Professor McBryde told the ABC.

"Ideally, we would get AstraZeneca to older age groups and Pfizer to younger age groups. But we don't have enough Pfizer."

Professor McVernon said research over the next six months would look at the best approaches for children, balancing their health and education needs.

Data suggests children and adolescents are less likely to catch the virus and play a smaller role in transmission, but the evidence of the past 18 months does not reflect the impact of the Delta strain.

The Pfizer vaccine has been approved for use in children aged 12 to 15 and the Australian Technical Advisory Group on Immunisation on Monday recommended it for the most vulnerable teens.

The modelling guided the vaccination targets agreed in-principle by federal and state governments last week.

A 70 per cent threshold is needed for lockdowns to be less likely, and 80 per cent coverage of the adult population would likely unlock international borders. But no deadlines have been set.

Australian Associated Press