Australia approves world-first single-dose vaccine to curb koala chlamydia epidemic

A federal regulator has approved a world-first, single-dose vaccine designed to curb a widespread chlamydia epidemic that has decimated Australia’s wild koala populations across much of the east coast.

Scientists at the University of the Sunshine Coast (UniSC) spent more than a decade developing the vaccine, which the university said in a multi-year clinical program reduced the likelihood koalas develop symptoms during breeding age and decreased mortality from the disease in wild populations by at least 65 percent. The vaccine does not require a booster, researchers said, a feature they called crucial for administering shots to wild and rehabilitated animals.

Chlamydia in koalas is transmitted through close contact or mating and can cause urinary tract infections, painful eye disease, blindness and infertility. The disease has been implicated in as much as half of koala deaths in some wild populations, and infection rates in individual colonies can be as high as 70 percent, researchers said.

Dr. Peter Timms, a microbiologist at UniSC who helped lead the work, said the team hoped to secure major funding to roll out the vaccine nationally to wildlife hospitals, veterinary clinics and into the wild. "Some individual wild colonies, where infection rate can be as high as 70 percent, are edging closer to extinction every day," he said.

Dr. Sam Phillips, who led the research, said the approval followed what the university described as the largest and longest study of wild koalas. The trial program tracked clinical outcomes over a decade, and the university reported a significant reduction in symptomatic disease and deaths where the vaccine was used.

Current treatments involve antibiotics, but treating infected koalas can have unintended consequences. Antibiotic regimens can disrupt the gut bacteria koalas rely on to digest eucalyptus leaves, their only food source, and can lead to starvation in treated animals.

Koalas face multiple threats beyond disease, including land clearing, bushfires, drought and urbanisation. Conservation groups and some scientists estimate there may be as few as 50,000 koalas remaining in the wild across Australia, though counts vary by region and methodology.

The vaccine approval comes a day after the New South Wales government announced it would reserve 176,000 hectares of state forest toward the proposed Great Koala National Park, a move aimed at securing habitat for the species. NSW Environment Minister Penny Sharpe said the park will "ensure koalas survive into the future so our grandchildren will still be able to see them in the wild." The park is expected to protect more than 12,000 koalas and provide habitat for more than 100 other threatened species, officials said.

UniSC researchers emphasized the vaccine is an immediate tool to reduce disease-driven deaths while broader conservation measures continue. The university said it will now seek funding and logistical support for production, distribution and administration through wildlife hospitals, rehabilitation centres and targeted field programs.

Officials did not release a detailed national rollout timetable following approval, and researchers said further coordination with government agencies, conservation groups and veterinary services will be needed to prioritise areas for deployment and to monitor long-term effectiveness in different population contexts.

The approval marks a notable milestone in wildlife disease management that researchers said could help stabilise and recover koala populations when combined with habitat protection and other conservation efforts.