Australia has made history with the approval of a world-first vaccine designed to protect one of its most beloved creatures—the koala—from the devastating effects of chlamydia. Following more than a decade of rigorous research led by microbiologist Peter Timms at the University of the Sunshine Coast (UniSC), the single-dose vaccine was officially greenlit by the Australian Pesticides and Veterinary Medicines Authority in June 2025, with the announcement made public on September 15. The milestone is being hailed as a breakthrough in wildlife conservation, offering new hope for a species teetering on the brink of extinction.
Chlamydia, caused primarily by the bacterial strain Chlamydia pecorum, is no minor nuisance for koalas (Phascolarctos cinereus). According to NPR, the disease is a leading cause of infertility and death among wild koala populations. In some colonies across Queensland and New South Wales, infection rates have soared to as high as 70%. The consequences are dire: blindness, urinary tract infections, infertility, and, in severe cases, an agonizing death. "Some individual colonies are edging closer to local extinction every day, particularly in South East Queensland and New South Wales, where infection rates within populations are often around 50 percent and in some cases can reach as high as 70 percent," Timms explained in a university statement cited by NPR.
Chlamydia is transmitted in several ways: through mating, infected discharges, at birth, and notably from mother to joey via pap—a nutrient-rich, feces-like substance essential for young koalas to digest eucalyptus leaves, their sole food source. This complex transmission web has made the disease almost impossible to control through traditional means. Antibiotics, the standard treatment, are not only ineffective at preventing reinfection but can also wreak havoc on the koala’s gut bacteria, which are crucial for digesting eucalyptus. As the University of the Sunshine Coast noted, this can lead to starvation—a grim fate for an animal already facing mounting threats.
The new vaccine, the result of more than 15 years of dedication and collaboration, is a scientific feat. Developed by Timms and his team, the vaccine is based on the major outer membrane protein (MOMP) of Chlamydia pecorum and contains six components: proteins from three different chlamydia strains and an adjuvant to boost the immune response. The best part? It requires only a single dose, with no need for a booster—an essential feature for treating wild animals. "We’ve purposely developed a vaccine that only requires one shot," Timms said in a video posted by UniSC. "For a wild animal like the koala, that is what you really need."
Field trials have shown remarkable results. As reported by NewsNation, the vaccine reduced mortality in wild koalas by at least 65% and lowered the likelihood of developing chlamydia symptoms during breeding age. In some cases, it even reversed existing symptoms in already-infected animals. Sam Phillips, a senior researcher at UniSC, noted, "It’s based on Chlamydia pecorum's major outer membrane protein (MOMP), and offers three levels of protection—reducing infection, preventing progression to clinical disease and, in some cases, reversing existing symptoms." A study led by Phillips and published last year found the vaccine reduced deaths from chlamydia by 64% during a koala's breeding age.
The approval means the vaccine can now be deployed in wildlife hospitals, veterinary clinics, and, crucially, in the field to protect at-risk koalas. According to the Associated Press, the permit authorizing use of the vaccine is valid through June 2027. The next big hurdle is securing the funding and logistical support needed for a widespread rollout. Timms acknowledged, "Now that the vaccine is approved, the next step is to secure funding for the rollout, so that veterinary teams can vaccinate at-risk koalas in the field."
The vaccine’s arrival comes at a critical juncture for koalas. Over the past two decades, wild populations have plummeted, battered by disease, habitat loss, climate change, and road collisions. The species is listed as endangered in Queensland, New South Wales, and the Australian Capital Territory. A 2020 assessment from the New South Wales government warned that koalas could become extinct by 2050 if current trends continue.
Federal, state, and local governments have rallied behind the vaccine’s development, with the federal government’s 76 million AUD ($50 million) Saving Koalas Fund playing a notable role. "We know that koalas need help to fight diseases like chlamydia. It’s a widespread threat impacting their reproductive health and causing infertility," said Environment Minister Murray Watt in a statement carried by multiple outlets.
Yet, not everyone in the conservation community is convinced that vaccination alone is the answer. Deborah Tabart, chair of the Australian Koala Foundation, voiced skepticism about the feasibility of vaccinating the entire wild koala population, which her organization estimates to be fewer than 100,000. "At the risk of sounding flippant, how can anyone be so delusional as to think that you can vaccinate 100,000 animals? It’s just ridiculous," Tabart told the Associated Press. She emphasized that habitat loss—driven by wildfires and urban expansion—remains the most significant threat to koala survival. "I accept that chlamydia is an issue for koalas, but I also want people to understand that they’re sick because they haven’t got any habitat," she added.
Other conservation groups, like the Queensland Conservation Council, welcomed the vaccine but echoed the call for greater focus on habitat preservation. "It’s really good news. Chlamydia is one of the key stresses that has been putting pressure on koala populations," said Dave Copeman, the council’s director. "Koalas were at risk before chlamydia outbreaks, and they will remain at risk even if we manage chlamydia perfectly, because we keep on destroying their habitat."
Koalas are more than just a symbol of Australia—they are a vital part of the country’s natural heritage, sharing the spotlight with kangaroos and wombats as iconic marsupials. Their unique biology, including a eucalyptus-only diet and two opposing thumbs for climbing, makes them fascinating and vulnerable in equal measure. The new vaccine, while not a panacea, represents a bold step forward in the fight to save them from one of their deadliest foes.
As the first vials are prepared and veterinary teams ready their equipment, Australia finds itself at a crossroads. The chlamydia vaccine offers a potent new weapon in the battle for koala survival, but its true impact will depend on whether it is paired with determined efforts to protect and restore the forests these marsupials call home. With extinction looming as a real possibility by 2050, the race to save the koala has never felt more urgent—or more hopeful.
