More than seven million people will be able to get a fourth dose of a Covid-19 vaccine after Australia's leading immunisation body updated its advice.
From July 11, people over 50 will be recommended to receive a fourth vaccine dose or second booster shot.
Those between 30 and 49 years old will from Monday be able to have a fourth dose if they choose.
The decision from the Australian Technical Advisory Group on Immunisation (ATAGI) comes amid rising numbers of virus cases across the country, fuelled by more transmissible strains of the Omicron variant.
Previously only those over 65, in aged or disability care, or immunocompromised were eligible.
ATAGI said the timing between vaccine doses or prior infection, whichever came first, would also be reduced from four months to three months.
The vaccine group did not extend eligibility for the fourth dose to those under 30 due to uncertainty as to whether the benefits outweighed the risks among the population group.
Health Minister Mark Butler said 7.4 million people would be able to get their fourth dose from Monday.
As of Thursday, 60% of people over 65 have had a fourth Covid-19 vaccine.
The vaccine body also said it was concerned the take up of booster doses had not been high enough.
ATAGI said it had noted the number of infections had increased and was placing a strain on the hospital system, noting it was expected to get worse in the coming months.
Mr Butler said it was critical for people eligible for a fourth dose to get the vaccine as soon as possible.
"The vaccine experts on the Australian Technical Advisory Group on Immunisation have recommended it - and the government has accepted this advice," he said in a statement.
"We are in the early stages of a third Omicron wave and our government is absolutely committed to making sure as many people as possible are protected."
However, Australian National University infectious diseases expert Professor Peter Collignon said those who were more vulnerable to the virus should still be prioritised.
"By looking at everybody for this, we're missing the people who are most at risk," he told Sky News on Thursday,
"By doing the whole population as we're doing, and implying almost everybody's equal, we're missing the people who are dying the most, and that's those who are older."
Latest 24-hour Covid data from Australian states
NSW: 13,343 cases, 22 deaths, 1822 in hospital with 62 in ICU
Victoria: 10,265 cases, 12 deaths, 592 in hospital with 30 in ICU
Tasmania: 1728 cases, no deaths, 80 in hospital with three in ICU
NT: 353 cases, no deaths, 19 in hospital with none in ICU
WA: 6387 cases, eight deaths, 240 in hospital with 12 in ICU
SA: 3762 cases, one death, 254 in hospital with 12 in ICU