As of late March, 10 cases of measles have been confirmed in Western Australia, and the latest exposure alert shows why vaccination rates matter so much. Cases of measles in returned overseas travellers have increased across Australia, particularly among those returning from South and Southeast Asian countries.
The numbers tell a story of vulnerability. Measles vaccination rates for two-year-olds in WA have recently decreased to 91 per cent; to achieve community immunity and prevent outbreaks, at least 95 per cent of a population needs to be vaccinated. That four percentage point gap, accumulated across a whole population, is exactly where outbreaks find room to spread.
The exposure sites revealed by the WA Department of Health Director of Communicable Disease Control Directorate, Paul Armstrong, tracked the infected traveller across Perth's everyday spaces. St John of God Midland Hospital's emergency department was listed twice on March 13. Woolworths stores in Ellenbrook and Aveley, Kmart in Ellenbrook, shopping centres and a Mount Hawthorn restaurant all appeared on the alert. Most recent cases visited multiple locations in Perth while infectious (including Perth Airport terminals).
The threat posed by measles is not a theoretical one. Measles is one of the most highly infectious communicable diseases. Up to 9 out of 10 non-immune people who are exposed to an infectious case will become infected themselves. The virus travels on air currents that do not respect the boundaries of individual choice.
Behind the falling vaccination numbers lies a problem of access and attention rather than mere refusal. In 2024, 1 in 3 children received the first dose of the measles, mumps, and rubella (MMR) vaccine late, putting children at risk of catching measles at a younger age. Competing demands on parents' time, difficulty booking appointments and the scattered nature of information about immunisation can all delay protection. While Australia has historically had high vaccination coverage, vaccination rates have been declining since the COVID-19 pandemic began. Immunization coverage overall has declined across the country by 2%-3% since the pandemic began.
The effectiveness of protection available is beyond question. Two measles vaccine doses are 99% effective at preventing infection from the virus. Measles combination vaccine is provided at no cost under the National Immunisation Program for children aged 12 months and 18 months. A state funded adult measles vaccination program is available for Western Australians born after 1965 who have not already received two doses of a measles-containing vaccine.
The scale of the global challenge adds pressure. As of March 12, 2026, 1,362 confirmed measles cases were reported in the United States in 2026, with outbreaks in countries that Australians regularly visit. The question facing WA Health and state governments across the country is whether the systems managing vaccine uptake can recover ground lost during the pandemic before the gaps widen further.
For people who visited the listed exposure sites, measles typically develops around 10 days after being exposed to the virus, but this can vary from 7 to 18 days. Checking vaccine records is free and can be done through the Department of Health website. If vaccination history is uncertain, WA Health's measles alert page provides updated information on exposure sites and symptoms to watch for.