Australians with lower levels of education and household income are significantly less likely to have received a third or fourth COVID-19 vaccine, according to a new study from The Australian National University (ANU).
The results from the representative survey of more than 3,500 adult Australians also show those born in a non-English speaking country are less likely to have received a fourth dose.
Study lead author Professor Nicholas Biddle said the lack of uptake is putting these groups at heightened risk.
"Australia's COVID-19 vaccine program is stalling. The proportion of Australians with two doses who go on to receive their third or fourth dose is low compared to many other countries," Professor Biddle said.
"This study helps explain some of the reasons why."
Department of Health data shows more than 20 million people over the age of 16 have received at least one COVID vaccine dose. In contrast, only 4.8 million people over the age of 16 have received four doses.
According to the ANU study, the age group with the lowest uptake of a third or fourth dose is those aged 25-34.
"For example, only 62.5 per cent of people aged 25 to 34 have had their first booster," Professor Biddle said.
"Those who have less confidence in governments or self-identify as being right wing in their political views are also less likely to have received a booster.
"Whereas those who watch free-to-air TV, read newspapers, or listen to the radio on a daily basis were much more likely to get boosted. This reiterates the importance of news sources when it comes to public opinion about the vaccine."
Australians who have tested positive for COVID-19 were far less likely to have received a third or fourth dose.
Professor Biddle said this could be a key reason why booster uptake has stalled in Australia.
"This is partly because there are restrictions on receiving a booster soon after an infection. It may also be that people perceive there to be a lower risk of COVID-19 if they have been infected," he said.
"There could be some benefit in reminding people once they've become eligible again to receive a third or fourth dose."
Professor Biddle believes this data could help with messaging around the COVID-19 vaccine to make sure the right groups are being targeted.
"Since around April 2022, the trajectory of booster uptake appears to have flattened," he said.
"Without high rates of booster uptake, it is more difficult for a country like Australia to continue to maintain minimal COVID-19 related restrictions without seeing high levels of hospitalisation and mortality."
Since the start of the COVID-19 period, the ANU Centre for Social Research and Methods COVID-19 Impact Monitoring Surveys has been tracking wellbeing, attitudes, and behaviours of adult Australians since the start of the COVID-19 period.
The survey data is available for download through the Australian Data Archive.