Govind Tekale
A new study has identified a significant gap in Australia’s measles protection, finding that 1.7 million Australians — approximately 7% of the population — lack immunity against the highly contagious disease.
The research, conducted by the National Centre for Immunisation Research and Surveillance (NCIRS) and led by Zoë Crocker, found that measles immunity across Australia stands at 93.3%, falling short of the World Health Organization’s target of 93-95% needed to maintain herd immunity. The findings are being published in the Australian and New Zealand Journal of Public Health.
“That is not good enough. We are at risk of major outbreaks,” said Prof. Adrian Esterman, commenting on the immunity gap.
The vulnerability extends across multiple age groups. Infants not yet eligible for vaccination represent one susceptible population, as do people born between 1977 and 1983, who likely received only a single measles dose before the two-dose vaccination schedule was introduced. Adults born between 1993 and 1995, as well as those born around 2000 and those aged 60 and older, also face elevated risk.
The timing of the findings is significant given a sharp rise in measles cases. Australia has recorded 113 measles cases so far in 2026, a dramatic increase from just seven cases in 2022. Last year saw 181 cases, with 57 in 2024 and 26 in 2023, illustrating an accelerating upward trend.
The trend is particularly concerning given Australia’s measles elimination status, achieved in 2014. That achievement now faces growing pressure as childhood vaccination coverage has declined for the fifth consecutive year in 2025.
Much of the recent transmission involves young adults aged 20-40 who contracted measles while traveling to endemic regions in Southeast Asia, particularly the Philippines, Vietnam, and Thailand. As these travelers return to Australia and encounter unvaccinated or under-vaccinated populations, transmission risks increase.
The NCIRS study provides the most comprehensive assessment of measles immunity gaps in Australia in recent years, using serological data to determine protective antibody levels. The findings underscore vulnerabilities in specific birth cohorts that may have been overlooked in routine surveillance.
Public health experts argue the data warrants immediate action to boost vaccination coverage and close immunity gaps before a larger outbreak occurs. The combination of below-target herd immunity levels, declining childhood vaccination uptake, and rising case numbers creates conditions for potential resurgence of a disease that once killed thousands annually before vaccine introduction.
The research comes as health authorities worldwide grapple with measles resurgence following years of pandemic-related vaccination disruptions. Australia’s situation mirrors concerns raised in other developed nations experiencing similar immunity erosion and case increases.
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