Australia needs to vaccinate 85% of its entire population, including children, to achieve herd immunity against the Delta COVID-19 variant, according to new modelling.

The nation’s current plan of opening up when vaccination levels reach 80% of adults (or 65% of the total population) falls “far short” of herd immunity, say the authors from James Cook University in Queensland and Melbourne’s Monash University. 

Their modelling shows the current mixed vaccine program – immunising over 60s with AstraZeneca and under 60s with Pfizer – will not achieve herd immunity unless 85% of the population, including 5-15 year-olds, are fully vaccinated.

Nevertheless, if herd immunity is not achievable, high rates of vaccination still provide protection against hospitalisation and death, the model shows.