While more than 30 per cent of eligible Australians are yet to have their third COVID-19 shot, the elderly and vulnerable will from Monday begin receiving a second booster ahead of a predicted winter infection surge.
The groups will include those 65 or older, Indigenous Australians aged at least 50, disability care residents and the immunocompromised.
An estimated 4.7 million people will be eligible to get a fourth dose but it is expected fewer than 200,000 will meet requirements at the start of the rollout.
People can have a second booster shot four months after receiving their first.
A parliamentary hearing was told on Friday eligibility numbers will be "relatively small" initially, with the bulk of people more likely able to book vaccination appointments through May and June.
Health department secretary Dr Brendan Murphy says the fourth jab will be critical in the effort to protect at-risk Australians ahead of winter, with a surge in cases of both the virus and influenza looming.
"The single most important thing we can do to protect people with underlying medical conditions, people with disability, people at risk of severe COVID, is to get as much vaccination - including full booster protection - as possible," he said.
The Australian Health Protection Principal Committee expects an infection peak will hit in mid-April in several jurisdictions.
Comprised of chief health officers from across the country, the group says it is considering recommending the removal of quarantine for COVID-19 close contacts.
It says isolation could be replaced by frequent rapid antigen testing, mask wearing outside the house and limiting access of close contacts to high-risk settings.
As of Sunday, more than 12,960,000 Australians had received a first booster vaccine. Almost 20 million have had at least their first vaccine shot and roughly 900,000 remain unvaccinated.
More than 47,000 new COVID-19 infections and 17 virus-related deaths were reported across the country on Sunday.
There are still nearly 504,000 active cases Australia-wide. Almost 2600 patients are being cared for in hospital wards, 103 of them in ICUs.
LATEST 24-HOUR COVID-19 DATA FROM ACROSS AUSTRALIA:
NSW: 16,807 cases, 11 deaths, 1355 in hospital, 50 in ICU
Victoria: 9008 cases, two deaths, 307 in hospital, 18 in ICU
Queensland: 8478 cases, no deaths, 418 in hospital, 16 in ICU
ACT: 718 cases, no deaths, 41 in hospital, two in ICU
Northern Territory: 309 cases, no deaths, 14 in hospital, one in ICU
Western Australia: 6439 cases, three historical deaths, 221 in hospital, seven in ICU
South Australia: 4096 cases, one death, 188 in hospital, eight in ICU
Tasmania: 1683 cases, no deaths, 37 in hospital, one in ICU.
Australian Associated Press
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