The news comes as Australia's vaccine advisory body approved COVID-19 booster shots for teenagers aged 16 and 17.

The Australian Technical Advisory Group on Immunisation (ATAGI) provided advice that a third dose of the Pfizer vaccine was safe and effective for teenagers.

Health Minister Greg Hunt says the third jab is integral to being better protected against the Omicron variant as Australia still records tens of thousands of cases each day alongside dozens of deaths.

It comes as Australia's primary vaccine advisory body, ATAGI, considers 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.

"That's a process that is being considered," Mr Hunt said.

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.

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.

There are also concerns Australia is set to face the dual threat of a fresh Omicron wave and the first major surge of flu cases since the pandemic began in coming months.

That's the assessment of the country's chief medical officer Paul Kelly, who said winter would bring fresh challenges to Australia's COVID-19 response.

While Omicron cases have begun to plateau in several jurisdictions, Professor Kelly on Wednesday told a COVID-19 committee hearing that new outbreaks were likely to hit during the colder months.

"There will be another wave of Omicron, most likely in the winter," he said.

"Every June since 2020 there has been a wave of COVID in Australia and other southern hemisphere countries."

Professor Kelly said the coming winter would also bring with it the additional risk of rising flu cases.

Instances of the flu have largely fallen in Australia since 2020 in the wake of the pandemic, following lockdown measures being enacted during traditional flu seasons in populous states.

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However, the chief medical officer said a spike in the flu should be anticipated in 2022.

"There was not a winter surge of the flu last year, and flu in the northern hemisphere is still less than usual, but the flu has not disappeared from the world," Prof Kelly said.

"With two years of no flu, we will probably have (a flu season) and we are prepared for all eventualities."

Prof Kelly said the rollout of flu vaccines would run alongside the rollout of the COVID-19 booster shots in coming months.

There were a further 70 COVID-19 deaths reported on Tuesday, with 27 of those reported in NSW, 25 from Victoria, 16 in Queensland and one in both South Australia and the Northern Territory respectively.

Another 40,090 virus cases were reported nationwide, with Victoria having 14,553, NSW having 11,807 and Queensland detecting 9630 infections.

There were a further 1723 cases in South Australia, 1133 in the Northern Territory, 666 in Tasmania, 549 in the ACT and 29 in Western Australia.