Australia was certified measles-free by the WHO Western Pacific Regional Office in 2014, meaning sustained local transmission of the same chain of virus has not occurred for over 12 months. We still see measles every year. The cases you read about in the news are nearly all imported, brought in by returning travellers, with limited secondary spread before public-health response contains them.
The geometry of importations
Measles is the most contagious disease known to medicine. R0 is 12–18, meaning one case in a fully susceptible group infects 12–18 others. In an aircraft, a hotel lobby, a primary-school classroom, a clinic waiting room, a few minutes of shared air is enough. The virus survives in the air for up to two hours after the infected person leaves.
Australia receives millions of international arrivals per year, and measles is still circulating widely in countries across South-East Asia, Africa, the Middle East and parts of Europe. The arithmetic of any year is: how many of those travellers arrive incubating measles, how susceptible are the people they share air with, and how quickly does public health get to it.
Two layers of defence
Layer 1, herd immunity
Australia’s two-dose MMR coverage at age 5 is around 93–94%, comfortably above the 92–95% needed in principle for measles herd immunity (see our herd immunity post). That national figure hides clusters of lower coverage, particularly in some inner-city and seaside Victorian LGAs and in pockets of NSW. Those clusters are where introduced virus finds susceptible people.
Layer 2, public-health response
When a measles case is notified, the local public-health unit moves quickly: contacts traced, exposure events identified, susceptible contacts offered post-exposure MMR within 72 hours (or normal human immunoglobulin within 6 days) where eligible. Communications go out to GP networks, schools, and the public. This response is the difference between a cluster of 3 cases and an outbreak of 30.
Where the adult immunity gap sits
The childhood schedule of two MMR doses dates from the late 1990s in Australia. People born between roughly 1966 and 1994 were vaccinated under earlier schedules that often included only one dose, or no dose at all if they were thought to have had natural measles. Many of them did not have natural measles. As they aged past childhood without testing or boosters, they accumulated as the under-protected adult cohort.
This is the cohort the Victorian MMR catch-up program for adults aged 20–59 is designed to close. It provides a free MMR vaccination to anyone in that age group who has not had two documented doses, regardless of Medicare status, funded through to at least 30 June 2026. For more, see our MMR catch-up post.
What outbreaks tell us
- Hospital exposure events. Many imported cases present to emergency departments before measles is suspected. EDs are high-density, high-throughput environments, vaccination of healthcare workers is critical (see our healthcare worker vaccination post).
- Childcare and school clusters. Pre-school children may have had one dose but not the second. Catch-up matters.
- Family clusters. Imported cases often spread first to household contacts, the inner ring. Adult catch-up vaccination protects the family unit.
- Inner-city LGA clusters. Pockets of vaccine hesitancy, often correlated with particular parenting and lifestyle subcultures, leave some communities below threshold even when the national figure looks fine.
Where this is heading
Globally, measles is rising. WHO recorded a multi-fold increase in measles cases in Europe and the Eastern Mediterranean in recent years, driven by COVID-era disruption to routine vaccination, persistent hesitancy, and conflict-affected regions losing programmatic capacity. Australia’s elimination status is durable so long as we maintain coverage and respond to importations quickly, but it isn’t a given.
What you can do
- Pull your AIR record from myGov and confirm you have two documented MMR doses.
- If you don’t, and you’re aged 20–59, the Victorian catch-up program covers you free.
- For travel, confirm MMR status at least 2 weeks before departure.
- Make sure your kids are up to date for the 12-month and 18-month doses, before international travel and before any clustering of cases in your area.
Sources & further reading
General information only. This article is educational and is not a substitute for personal medical advice. Your immuniser will confirm eligibility and contraindications on the day.
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