From February 20, all adults will be able to get a booster shot provided their last dose or COVID-19 infection was six or more months ago.

The Australian Technical Advisory Group on Immunisation gave the federal government the tick on adult boosters based on the current "context" in early 2023 following a renewed surge in cases earlier this year.

COVID-19 cases, and related hospitalisations, around Australia have continued to slide after peaking in December during a fourth wave of Omicron.

The powerful advisory group added any vaccine booster shot is expected to be beneficial but Omicron-specific mRNA boosters were the preferred option.

Four million Omicron-specific booster doses are available immediately with a further 10 million arriving later in February, the federal government said.

Health Minister Mark Butler, who will make the announcement alongside Chief Medical Officer Professor Paul Kelly on Wednesday morning, urged those at risk of severe risk of illness to go out and get their latest jab.

"If you're 65 or over, or you're an adult at risk of severe COVID illness, and it's been six months since your last booster or infection, it's now time for a booster," Mr Butler said.

"The government has secured millions of doses of Omicron-specific boosters, with millions more arriving this month, in the largest one-month arrival since late 2021."

An additional booster is not yet recommended for those under 18, according to the latest advice, except where children have health conditions that would put them at risk of severe illness.

Mr Butler and Aged Care Minister Anika Wells will also write to aged care providers regarding the new rules surrounding extra boosters.

Further changes to booster advice will be affected by surveillance of infection rates, new variants and vaccine effectiveness, the advisory group said.

Australia's medical regulator gave the first two Omicron-specific boosters a provisional green light last month. The Pfizer booster, which targets the BA.4 and BA.5 variants, will be for those aged 12 and over.

A booster for the BA.1 variant and original bivalent vaccine - which is when the original virus strain is included in the vaccine - was approved late last year.

The Therapeutic Goods Administration said studies showed the vaccine helped produce neutralising antibodies against the variants and original strains one month after the booster.

It also provided protection against a number of other variants.

"Evidence from extensive use in the US and Europe over recent months has also shown that this booster provides clear reductions in hospitalisation and death," the regulator said.

- with AAP

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