GROUNDBREAKING research led by the National Centre for Immunisation Research and Surveillance (NCIRS) has revealed that an estimated 1.7 million Australians, or 6.7% of the population, did not have sufficient immunity to measles in 2019. In a world-first, the study combined national immunisation register data with multiple serosurveys – studies…
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GROUNDBREAKING research led by the National Centre for Immunisation Research and Surveillance (NCIRS) has revealed that an estimated 1.7 million Australians, or 6.7% of the population, did not have sufficient immunity to measles in 2019.
In a world-first, the study combined national immunisation register data with multiple serosurveys – studies that test many blood samples to measure population immunity levels – to produce a detailed analysis of measles susceptibility across all age groups.
The study, which was published today in the Australian and New Zealand Journal of Public Health, found overall measles immunity in Australia was 93.3%, meaning that a significant minority of people were unlikely to have sufficient protection against measles if exposed to the virus in 2019.
Experts have warned that these immunity gaps may now be wider due to a continued decline in childhood vaccination coverage since the COVID-19 pandemic.
The findings come as global measles outbreaks increase and imported cases continue to reach Australia, with national measles notifications rising from single figures in 2022 to 181 in 2025, and 113 cases recorded so far in 2026.
“Our study represents the most comprehensive national estimate currently possible using Australia’s most recent serological data and whole-of-population immunisation record data,” lead author Zoe Croker, an epidemiologist and data analyst at NCIRS, said.
“Australia remains a measles elimination success story, but our findings show we’re closer to the minimum level of population protection needed to prevent outbreaks than many people might expect,” Croker warned, referring to the World Health Organization (WHO) target range of 93-95% immunity needed for herd protection.
Susceptibility was highest among infants who were too young to receive their full measles vaccination schedule, as well as Australians born from the late 1970s onwards.
“While we have maintained our measles elimination status since 2014, protection isn’t shared evenly across the population, and the margin for error is relatively small,” Croker explained.
The NCIRS is urging anyone born during or since 1966 who does not have documented evidence of two vaccine doses or immunity to get vaccinated, particularly those planning to travel overseas.
Read the study HERE. KB
