The Australian Technical Advisory Group on Immunisation (ATAGI) is expected to discuss at their next meeting on Wednesday whether more people should be eligible for a fourth dose.
A fourth vaccination is currently only available for people over-65 and vulnerable Australians.
Hospitals are feeling the pressure from rising case numbers and all available tools should be deployed to help, Melbourne School of Population and Global Health head Nancy Baxter says.
"We know the fourth dose has a significant effect," Professor Baxter told the Seven Network on Tuesday.
"The protection from getting COVID after you have a dose of the vaccine goes up quite quickly."
Meanwhile, some states and territories could reintroduce mask mandates to curb the case increase.
As more transmissible strains of the Omicron variant emerge, discussions are underway about other measures to stop the spread.
In Queensland, talks are ongoing over whether mask rules would return in some settings, Premier Annastacia Palaszczuk said.
"We are not doing a mask mandate, but there are discussions happening about urging people in certain situations to wear masks," she said.
ACT Health Minister Rachel Stephen-Smith said a fresh mask mandate was not being ruled out.
However, she indicated other options were being considered.
"There is a view that mandatory mask requirements might not be as effective as they have been in the past, partly because those people who are willing to wear masks are already doing so," she said.
Victoria's Chief Health Officer Professor Brett Sutton said the BA.4 and BA.5 strains had become dominant in Geelong and Melbourne wastewater detections.
They were expected to overtake the BA.2 strain to become dominant across the state.
"This is because the strain has a greater ability than BA.2 to evade immunity provided by vaccination and earlier COVID-19 infection," Prof Sutton said on Monday.
Hospitalisations on Monday had reached 3511 across the country, the highest levels since February during the height of the Omicron wave.
Nearly 30,000 infections were reported nationally on Monday, with experts warning case numbers will climb even further as winter progresses.
Despite the rise in cases, border restrictions brought in as a result of the pandemic will be enforced for their final day on Tuesday.
Changes to the Biosecurity Act will come into effect on Wednesday, with international arrivals no longer needing to declare their vaccination status to enter the country.
LATEST 24-HOUR COVID-19 DATA:
NSW: 10,504 cases, 14 deaths, 1782 in hospital with 58 in ICU
Tasmania: 1588 cases, two deaths, 76 in hospital with two in ICU
Victoria: 8740 cases, 16 deaths, 543 in hospital with 28 in ICU.
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