On Friday, Prime Minister Scott Morrison announced the government had secured an extra 20 million Pfizer doses overnight, meaning Australia will receive a total of 40 million Pfizer doses in 2021.
"It is anticipated that these additional 20 million doses will be available in quarter four of this year, that's our current instruction," he said.
He was addressing the media following a national cabinet meeting where state and federal leaders discussed potential changes to international travel restrictions, future domestic and family violence support, and the "recalibration" of the COVID-19 vaccine rollout hollowing the ATAGI advice.
"Our focus remains on the delivery of 1A and 1B cohorts for the vaccination roll out," Mr Morrison said.
"This is particularly important because we're substantively talking here about people who are over the age of 50."
Australia secures 20 million additional Pfizer vaccines
Health Minister Greg Hunt said Pfizer had indicated Australia would see an expansion of supply in April and May, before a "nearly doubling" in July which "will track through to the rest of the year".
"Then the 20 million that has just been purchased, at this point in time is settled for the fourth quarter, but we are working with them on the possibility of bringing forward as many of those doses as possible," Mr Hunt said.
Under the ATAGI recommendations announced on Thursday night, adults under 50 can get the first dose of the AstraZeneca COVID-19 vaccine in circumstances where the benefits clearly outweigh the risk for that individual.
Those who have already received their first AstraZeneca dose without serious adverse effects can get their second.
Mr Morrison on Friday reiterated that the updated AstraZeneca advice didn't represent a prohibition.
"It recommends and notes that the risk of these side effects are remote. They are very rare," he said.
"We're talking in the vicinity of five to six per million, which is a rather rare event. But it must be acknowledged. And it's important so Australians can make informed decisions."
National cabinet discusses future of travel
Mr Morrison said national cabinet had agreed to seek advice on what a successful vaccine rollout could mean for reopening Australia.
They want to know the thresholds they would have to meet before allowing vaccinated Australians to travel overseas and return without going into hotel quarantine - whether it's because they're going into home quarantine instead, or not quarantining at all.
"That will be a major change," the prime minister said.
Government announces Pfizer as preferred vaccine for those under 50
He said they're also seeking advice on the extent to which vaccinated Australians overseas could return home on the same basis.
There's also the potential for travel to and from low risk countries with similar vaccine arrangements.
"No one is saying that any of those things are coming in today," Mr Morrison said.
"But what we are working and planning for, and have tasked the medical professionals who advise us on, is what are the marks we have to meet to enable us to start opening up Australia more than we are now."
He said the successful of the new trans-Tasman travel bubble with New Zealand could offer greater confidence about similar arrangements with other countries.
"I've mentioned Singapore before as an obvious next choice, but at this stage that is still some time away."