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Federal government figures released on Thursday show 52.2 percent of the eligible population aged 65 and over have received their fourth jab for the virus, equating to more than 1.6 million people.
That was up 1.6 percent on the corresponding time last week.
In total and accounting for those aged under 65, more than 1.8 million Australians have received at least four doses of a Covid-19 vaccine.
People become eligible for their winter booster four months after their third vaccine dose.
Authorities continue to urge people to take up Covid-19 boosters and influenza vaccinations to help protect their families this winter.
Federal Health Minister Mark Butler issued a reminder on Thursday, coinciding with his announcement that children aged between 12 and 15 who are most at risk of severe disease can get their booster jabs from next Tuesday.
To be eligible, children have to be severely immunocompromised, have a disability with significant or complex health needs, or have complex and or multiple health conditions that increase their risk of severe Covid-19.
One or multiple of those categories can apply to children for them to be eligible.