Older and vulnerable Australians can receive a second COVID-19 booster dose ahead of a predicted surge of winter infections.

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 able to get the fourth dose but its expected less than 200,000 of them will be eligible at the start of the rollout.

People can have a second booster shot four months after receiving their first.

A Senate estimates hearing was told on Friday eligibility in the early stages will be "relatively small" with the bulk of people more likely to be able to book vaccination appointments in May and June.

Health department secretary Dr Brendan Murphy says the fourth jab will be critical to help protect at-risk Australians ahead of winter, with a surge of both virus and influenza cases 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.

Guidance has been provided to aged care facilities wishing to have a commonwealth vaccine administrator assist with the new rollout.

The Australian Health Protection Principal Committee says it's likely a peak of cases associated with a winter spike will hit in mid-April in several jurisdictions.

Comprised of chief health officers from across the country, the group says it is considering recommending quarantine be removed for close contacts of COVID-19 cases.

It says isolation could be replaced by other measures following the peak.

The recommendation would instead urge frequent rapid antigen testing, mask wearing outside the house and limiting access of close contacts to high-risk settings.

"Where quarantine is required, seven days remains appropriate at this time," the committee said on Friday.

"Removing quarantine at this time may lead to higher caseloads and a reduced capacity for the health system to provide some acute and elective services."

More than 54,000 COVID-19 infections and 26 virus-related deaths were reported across the country on Saturday.

LATEST 24-HOUR COVID-19 DATA FROM ACROSS AUSTRALIA:

NSW: 20,389 cases, 13 deaths, 1302 in hospital, 47 in ICU

Queensland: 9435 cases, six deaths, 422 in hospital, 15 in ICU

Victoria: 9149 cases, three deaths, 306 in hospital, 15 in ICU

Western Australia: 7822 cases, one death, 215 in hospital, six in ICU

South Australia: 4483 cases, two deaths, 184 in hospital, eight in ICU

Tasmania: 1840 cases, no deaths, 36 in hospital, one in ICU

ACT: 808 cases, no deaths, 43 in hospital, two in ICU

Northern Territory: 421 cases, one death, 14 in hospital, one in ICU.