Measles epidemiology in Australia: 2014 to 2024

Endemic measles was verified as eliminated in Australia in 2014. We describe Australian measles epidemiology, 2014-2024.

National measles notification data were analysed by age; sex; state/territory of residence; genotype; place of acquisition (overseas/Australia); vaccination status (number of doses); and outbreak reference ID (for clusters).

Between 2014 and 2024, there were 1,095 measles notifications (average annual notification rate 0.4 per 100,000 population per year). The highest annual notification rates were recorded in 2014 (1.4 per 100,000 per year) and 2019 (1.1 per 100,000 per year), when rates in the Northern Territory were 21.4 and 12.6 per 100,000 population per year, respectively. Although notification rates were highest among infants < 1 year of age (average 3.8 notifications per 100,000 population per year), people aged 20-49 accounted for 57.2% of total notifications (n = 626). Of cases with a known immunisation status (n = 766), there were 513 cases (66.9%) who reported being unvaccinated; 20.1% (n = 154) reported having received one dose of MMR vaccine prior to infection; and 12.1% (n = 93) reported two or more doses. For notifications where country of acquisition was available (n =1,077), just over half of cases (55.1%) were acquired in Australia. Where measles was acquired overseas (n = 493), the most common countries of acquisition were Indonesia (n = 99; 20.1%), the Philippines (n = 82; 16.6%) and India (n = 52; 10.5%). There were 47 clusters during the reporting period, of which the largest involved 74 linked cases in 2019. Of recorded clusters, 44 (93.6%) had a source country outside of Australia. Notifications tended to peak each year in the months coinciding with the end of Australian school holiday periods.

Australia has sustained measles elimination since 2014; this review of measles epidemiology, demonstrating a predominance of unvaccinated returning international travellers 20-49 years of age, provides strong motivation for maintaining high routine two-dose coverage and promoting measles vaccination to adults travelling internationally.