1.7 million Australians are unprotected against measles

An estimated 1.7 million Australians, or 6.7% of the population, were susceptible (did not have sufficient immunity) to measles in 2019, a major new study led by the National Centre for Immunisation Research and Surveillance (NCIRS) has revealed.

The study, published today in the Australian and New Zealand Journal of Public Health, found overall measles immunity in Australia was 93.3%, meaning that almost 7 in every 100 Australians were unlikely to have sufficient protection against measles if exposed to the virus in 2019.

Experts warn that these immunity gaps may now be wider, as childhood vaccination coverage has continued to decline.

The findings come as global measles outbreaks increase and imported cases continue to reach Australia. Based on recent data from the National Notifiable Diseases Surveillance System (NNDSS), national measles notifications have risen sharply since 2022—from single digits to 181 in 2025, with 113 cases recorded so far in 2026.

The study is the first internationally to combine national immunization register data with multiple serosurveys (studies that test many blood samples to measure population immunity levels)—the latest of which was conducted in Australia in 2012—to produce a detailed analysis of measles susceptibility across all age groups.

“Our study represents the most comprehensive national estimate currently possible using Australia’s most recent serological data and whole-of-population immunization record data,” said Zoë Croker, an epidemiologist and data analyst at NCIRS and lead author of the study.

“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.”

“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. Importantly, population immunity may now be slightly lower than our 2019 estimate, given that childhood vaccination rates have declined since the COVID-19 pandemic.”

Who is most at risk?

The study found that susceptibility was highest among infants who were too young to receive their full measles vaccination schedule and among Australians born from the late 1970s onward. Every birth cohort from 1977 onward had at least 5% of its population estimated to be susceptible.

Many of these cohorts are now raising young families and are among Australia’s most frequent overseas travelers, increasing the chances of measles being introduced into households and communities. The study also found that people ages 15–35 accounted for half of the measles cases reported in Australia between 2008 and 2022.

“Measles is one of the most contagious diseases known. Even relatively small immunity gaps in communities can create opportunities for the virus to spread when cases are imported from overseas,” Croker said.

Maintaining Australia’s measles elimination status

Australia has maintained its World Health Organization (WHO)-certified measles elimination status since 2014.

While Australia’s national measles immunity is within the WHO target range of 93–95% for herd protection, it sits at the lower end of that range and is not distributed evenly across the population.

“There are likely to be communities, regions or groups where immunity gaps are substantially higher than the national average, raising the risk of local outbreaks if measles is introduced,” said Associate Professor Frank Beard, associate director at NCIRS and senior author of the study.

Several high-income countries, including Canada, Spain and the United Kingdom, have recently lost their measles elimination status amid rising global outbreaks and international travel.

“What’s happened overseas is a reminder that elimination status isn’t guaranteed—it has to be actively maintained. That means keeping our population immunity as high as possible,” Beard said.

What can Australians do?

Measles is highly preventable through vaccination, and Australian guidelines recommend measles vaccination for anyone born during or since 1966 who does not have documented evidence of two vaccine doses or immunity. This is particularly important for people planning to travel overseas, who have a higher risk of exposure.

The researchers are encouraging Australians in this group, particularly those planning international travel, to check their vaccination status and get vaccinated if not up to date.

“Check your records, talk to your primary care physician or other immunization provider, and get vaccinated if needed. If you’re not sure whether you’ve had two doses of a measles-containing vaccine, it’s safe to have one or two doses if needed,” Beard said.

“Protecting yourself helps protect your family, vulnerable babies and young children, your community, and Australia’s hard-won measles elimination status.”

Provided by
Public Health Association of Australia

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

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