From July 11, eligibility for a fourth vaccine dose – or second booster – will be expanded to include 7.4 million more people.

The Australian Technical Advisory Group on Immunisation recommended those over 50 receive a second booster.

The group also said those aged between 30 and 49 would be able to receive an additional booster if they chose to, but this was not a formal recommendation.

The decision follows a spike in COVID cases across the country, driven by a more transmissible strain of the Omicron variant, which has led to increased deaths and hospitalisations from the virus.

Previously only those over 65, in aged or disability care, or immunocompromised were able to get a fourth dose.

ATAGI said the timing between vaccine doses or prior infection, whichever came first, would also be reduced from four months to three months.

Health Minister Mark Butler said while there wasn’t a set target as to how many over-30s would get the fourth dose, a big uptake would be needed ahead of spiralling winter cases.

“This decision … will reduce severe disease and will relieve pressure from our hospital system,” he said in Adelaide on Thursday.

“There’s almost 10,000 points of primary care, pharmacies and GP surgeries where you can go and get this fourth dose. We have lots of capacity in the system.”

Butler said activity at vaccination clinics was 80 per cent less than at the height of the rollout last year.

As of Thursday, 60 per cent of people over 65 have had a fourth COVID-19 shot.

The vaccine body also said it was concerned the take-up of booster doses had not been high enough.

ATAGI said in a statement it had noted the number of infections had increased and was placing a strain on the hospital system, adding it was expected to get worse in coming months.

“Increasing the uptake of winter booster doses of COVID-19 vaccine in populations most at risk during this time is anticipated to play a limited but important role in reducing the risk from COVID-19 to individuals and pressure on the health care system,” the statement said.

ATAGI said other measures such as increased mask usage and more antiviral treatments being made available would also help with surging infections.

The vaccine group did not extend eligibility for the fourth dose to those under 30 because it is not known whether the benefits outweighed the risks among the population group.

-with AAP