Measles, diphtheria resurge in Australia as vaccination rates decline post-pandemic

For more than a decade, Australia had held something worth holding: the status of a country where measles no longer circulated. The virus that once marked childhood for generations—the fever, the cough, the telltale red rash—had been driven into absence through vaccination. Anyone born before the late 1960s carried immunity in their body, a record of having survived the disease itself. That was the old way. The vaccination campaign that followed made it the new way, and by 2014, the World Health Organisation declared Australia free of endemic measles transmission.

Then, in September 2026, a traveller returned from overseas carrying the virus. Within the Brighton Secondary School community in South Australia, it spread to three students and an adult in their 40s, who ended up hospitalised. Contact tracing extended to the Queen Elizabeth Hospital's emergency department, where the adult had spent more than 24 hours. By year's end, South Australia had recorded nine measles cases—the highest count since 2016. It was, as the state's Chief Public Health Officer Nicola Spurrier put it, a disappointing turn, though not entirely unexpected.

The disappointment ran deeper than one outbreak. Spurrier had watched vaccination rates decline year after year since the COVID-19 pandemic began. She had seen misinformation circulate in channels beyond scientific literature. Adrian Esterman, an epidemiologist at Adelaide University, pointed to practical barriers as well: parents stretched thin, difficulty accessing general practitioners, the friction of ordinary life making it harder to get children to vaccination appointments. But the problem extended beyond Australia's borders. Canada had lost its measles-free status. The United Kingdom had lost it. The United States was on the verge of losing it too. Measles was surging globally, and Australia was not isolated from that tide.

Measles was not alone in its return. Australia was simultaneously experiencing the largest diphtheria outbreak since records began in 1991. The count had climbed past 600 cases, with 22 in South Australia. The bacterial infection—striking the nose, throat, airways, or skin—was treatable with antibiotics, but vaccination remained the primary defence. Unlike measles, which had spread across a school, diphtheria was concentrating its damage in specific communities: Indigenous populations in outer regional and remote areas across four states and territories. The outbreak had begun to plateau in recent weeks as health authorities delivered more than 4,500 vaccines to communities in the far north and south-west, particularly in the APY Lands, where the majority of cases had occurred. Spurrier noted the community's response had been strong.

Esterman framed the broader pattern plainly. Measles, diphtheria, whooping cough—which had spiked nationally in 2024—were all childhood diseases making a comeback as vaccination rates fell. Eighty to one hundred years ago, these diseases had been absolute killers. Families had been large partly because parents knew many children would not survive infancy. Modern vaccination had rewritten that story so thoroughly that a generation had grown up without knowing what these diseases looked like. Now, as vaccination rates declined and misinformation spread, that knowledge was being tested again. The question was not whether these diseases could return—they were returning. The question was whether Australia could reverse course before the return became permanent.