Medical authorities have approved a new COVID-19 vaccine for use in Australia that offers protection from two strains of the virus.

As Australia deals with a fourth rise of COVID cases, the country's leading vaccine advisory body has approved the Pfizer bivalent vaccine for use as a booster.

The bivalent vaccine, which provides protection against the original strain and the Omicron variant, will be available from December 12 for people 18 and older.

The Pfizer next-generation vaccine is the second bivalent vaccine that has been approved for use following the rollout of the Moderna bivalent vaccine last month.

The Australian Technical Advisory Group on Immunisation said the new Pfizer vaccine was able to trigger a modest improvement in the immune response against both strains of the virus.

Health Minister Mark Butler said the new round of vaccines would be another tool to combat rising case numbers.

"The Australian government has added this next generation Pfizer vaccine to our armour against COVID-19," he said.

"This is a reminder to all Australians to make sure you are up to date with your COVID vaccinations. Now is the time to get your booster."

COVID case numbers have spiked in Australia in recent days, prompting experts to declare the start of a fourth wave of cases.

Vaccine boosters are available to people 16 years and older, while second boosters are available for those 30 years and older within three months of the first booster, or those over 16 if they are immunocompromised, living in aged or disability care.

ATAGI has also approved the paediatric Pfizer vaccine for at-risk children between six months old and five years old. That rollout will begin from mid-January next year.

The paediatric vaccines are being limited to children who are severely immunocompromised or who have a condition that put them at risk of COVID.