The term 'fully vaccinated' could be soon be replaced with 'up to date on vaccinations', as the government's vaccine advisory body weighs up other changes to the COVID-19 vaccine program.
ATAGI has been deliberating whether or not to change the definition of 'fully vaccinated' to require booster shots too.
That change has support from some state premiers, like Victorian Premier Daniel Andrews.
It is expected to hand over its advice to the federal government in the next fortnight.
But it is also likely to recommend dumping the term 'fully vaccinated' altogether, in favour up 'up to date on vaccinations'.
ATAGI chair Nigel Crawford said it would bring the COVID-19 vaccination program closer into line with other vaccination programs, like those administered to children.
"We think the best terminology is actually 'up to date with vaccination status', rather than 'fully vaccinated'," he told federal parliament's COVID-19 committee.
"That's a term that we've used in the childhood program.
"So essentially, as you have your children get vaccinated, we say are you 'up to date with your immunisations' at a certain date or point in time."
Dr Crawford said the term 'fully vaccinated' can be confusing.
He pointed out that currently, while most Australians are considered fully vaccinated with two doses of a vaccine, an immunocompromised person requires three doses.
Dr Crawford said 'up to date' would be more practical in future.
"There is some complexity at that individual-level advice, which then flows into the population, determination and the Australian Immunisation Register," he said.
Second Omicron wave expected in winter
Chief Medical Officer Paul Kelly told the committee he believed Australia would go through a second wave of Omicron infections during winter, as there were still many people who had not contracted the virus.
He said there was evidence that some people, particularly those aged over 50 and 60, had "withdrawn" from society over the last few months for fear of catching COVID-19 and so therefore had not been exposed to the disease.
"In the Northern Hemisphere, there has been increases usually starting in early winter, in each of the winters since the start of the pandemic.
"So will that actually happen this time, I can't say for certain but we should be — and we are indeed — planning for that eventuality.
"We may also have flu to cope with [then]."
Professor Kelly said Australians may have to deal with both COVID and the flu this year, after two years without an influenza season.
"Flu is not disappeared from the world, so with two years of no flu it's likely we will have a flu season; how bad that will be is speculation," he said.
The Chief Medical Officer said authorities had already ordered flu vaccines for the upcoming season.
When asked how long it would be until Australia was no longer faced with the pandemic, Professor Kelly delivered a sobering answer.
"The end is not yet in sight in terms of living with COVID," he said.
"The unfortunate news is we're pretty certain now that there won't be a freedom day as such; we will not be leaving this pandemic for some time."
