Some 370,000 teenagers aged 16 and 17 have become eligible for their third COVID-19 jab.
Health Minister Greg Hunt said the booster will better protect against the Omicron variant as Australia still records tens of thousands of cases each day alongside dozens of deaths.
Australia's primary vaccine advisory body, ATAGI, has recommended the third jab for those aged over 16, after the Therapeutic Goods Administration approved the Pfizer booster for the younger cohort on January 28.
The body is also considering raising the definition of fully vaccinated to three doses.
"I think it is more likely than not. That's my expectation," Mr Hunt told the Nine Network.
"(But) we want everybody to be boosted in any event."
The health minister has also written to Pfizer to encourage them to go through the process of making booster shots available to younger teens, but a full application is yet to be lodged with Australian regulatory health bodies.
"We are encouraging them to bring that forward ... at the earliest possible opportunity," Mr Hunt told the ABC.
Australia has surpassed 8.4 million booster shots, or just under 70 per cent of those eligible, administering over 200,000 third doses a day.
But a third of people in aged care are yet to receive their boosters despite vaccination teams visiting 99 per cent of all aged care facilities to offer the third dose.
It remains unknown how many of the almost 500 aged care residents who have died with COVID-19 this year had received a booster.
Aged Care Services Minister Richard Colbeck was unable to answer at a parliamentary committee on Wednesday, while Mr Hunt said the data was held by the states and yet to be passed to the Commonwealth.
The head of the country's vaccine rollout, Lieutenant-General John Frewen, said teams would be conducting second visits of facilities to vaccinate more aged care residents.
Senator Colbeck tried to play down claims of the aged care sector being in crisis, despite acknowledging the extreme stress and pressure staff and facilities are under.
ACT Health Minister Rachel Stephen-Smith says there has been a mismatch between what the federal government promised it would do and what was delivered on the ground, further impacting the sector.
"What we've seen throughout is promised support from the Commonwealth just hasn't been available," she told the ABC.
Aged Care Services minister Richard Colbeck says the aged care sector is not is crisis. Source: AAP
"(They) weren't able to come to the party to provide that additional staffing they had initially indicated they would do."
Ms Stephen-Smith says the Commonwealth ignoring system issues - such as wages in the sector - and instead choosing two $400 bonus payments, shows it isn't taking the situation seriously.
"COVID-19 represents a crisis but more broadly, there is a significant challenge right across the aged care sector in its sustainability and its capacity to particularly care for those most complex aged care patients," she said.
"The aged care services just aren't funded to support those people who have really high and complex needs."
