Scott Morrison expects everyone who wants a COVID-19 jab to be fully vaccinated by the end of the year.
The federal government previously walked back on several vaccinate targets, including ensuring everyone would have a first dose by October.
Now, the prime minister expects everyone who wants a jab will be able to receive two doses by the year's end.
"By the end of the year, people who have wanted to have the vaccine will have had that opportunity," Mr Morrison told 3AW Radio on Thursday.
But he also said no one could provide a guarantee Australia would be fully open by Christmas because of the unpredictability of the Delta strain.
The prime minister encouraged people who had received a shot of AstraZeneca to expedite their second dose.
His advice extends beyond locked-down Sydney to people in other parts of the country.
"If they are in a position to do that, then that is consistent with the license for AstraZeneca," Mr Morrison said.
"I need to get the whole country vaccinated as well and the sooner we get there and it can be done safely then we should."
Mr Morrison will on Friday thrash out modelling with the states to determine what level of vaccination coverage Australia needs to stop rolling lockdowns and border closures.
"Will we get there in one meeting? No, I dont think we will," he said.
Sydney and its surrounds will remain locked down until at least the end of August as the city struggles to contain a coronavirus outbreak.
Victoria and South Australia have emerged from lockdown after bringing their respective Delta outbreaks under control.
About 17 per cent of Australians aged 16 and older are fully vaccinated, leaving the country well behind similar nations five months into the rollout.