Burnet Institute director Brendan Crabb says current strategies to combat the country's caseload are not working.
"What the numbers say is that we're simply not winning," Prof Crabb told Seven's Sunrise on Saturday.
"The latest wave we just had ... was the worst wave we've had this year; more hospitalisations and more deaths."
Australia reported another 15,301 cases and 97 fatalities on Saturday, with the nation on track to record its 10 millionth case within a week.
Prof Crabb says there's an "attitude problem".
"We haven't quite grasped the fact that having lots of virus in our community is bad.
"We have to change to reduce transmission, to be intolerant of the amount of virus in our community."
US researchers have been analysing people who have repeatedly contracted COVID-19 and finding the risk of acute and chronic disease accumulates with each new infection.
Prof Crabb says the research is worrying.
"There is no wall of immunity built by infection against the impacts of infection," he said.
While "herd immunity" is real, he says the way to reach it is through vaccination, not infection.
The latest data shows about 14.2 million Australians have received three vaccine doses, while around 4.5 million have had a fourth.
The Australian Technical Advisory Group on Immunisation last month updated recommendations to say those aged 30 to 49 are eligible for a fourth shot and those 50 to 64 should also get one.
Older Australians were already able to receive a fourth vaccine.
The interval between doses or prior infection has also been shortened from four months to three.
Healthy adults under 30 are not yet eligible for a fourth jab.
LATEST 24-HOUR COVID-19 DATA:
Victoria: 2437 cases, 18 deaths, 438 in hospital with 29 in ICU
NSW: 4335 cases, 16 deaths, 1925 in hospital with 52 in ICU
ACT: 186 cases, no deaths, 120 in hospital with three in ICU
Queensland: 1166 cases, no deaths, 377 in hospital with 13 in ICU.
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