The Australian Technical Advisory Group on Immunisation on Friday released new recommendations for all people aged 12 and above with certain conditions or undergoing specific therapies.
A Pfizer jab is preferred for people two to six months after their second dose with a minimum interval of four weeks in exceptional circumstances.
Severely immunocompromised people who received their second dose more than six months ago should get another injection as soon as possible.
ATAGI will monitor evidence around duration of protection for immunocompromised people and provide further advice about waning vaccine protection or risk from variants of concern.
"ATAGI will provide further advice on booster doses for healthcare workers, older adults and the general population separately," the expert panel said in a statement.
Victoria reported 1838 new COVID cases on Friday, the highest single-day total of any state or territory since the pandemic began.
There were five more deaths across the state and 11 in NSW, which recorded 646 new local cases.
Finance Minister Simon Birmingham said COVID booster shots could be made available for some Australians as early as the end of the year.
"The government has procured tens of millions of booster shots available to Australians from the start of the year, from late this year if required," he told Sky News.
The timing of booster shots would depend on when someone who is fully vaccinated received their second dose.
The minister also defended spending hundreds of millions of dollars in taxpayer cash on dedicated quarantine facilities, which are still months away from operating.
Fully vaccinated Australians are expected to be allowed to quarantine in homes from next month rather than centres earmarked for Queensland, Victoria and WA.
Senator Birmingham said the sites could be used for future health and humanitarian crises, as well as a contingency for new coronavirus variants.
"While we will be living with COVID in the community, there will still need to be some safeguards," he said.
"There will be other cohorts of individuals potentially looking to move in and out of the country who aren't fully vaccinated, where we may have a cause or a need to use quarantine facilities."
Australia has fully vaccinated 59.3 per cent of its population aged 16 and above, while 81 per cent have received at least one dose.