In an island nation that is home to tons of dangerous creatures, koalas remain one of Australia’s most iconic wildlife representatives. Unfortunately, they are currently classified as endangered in Queensland, New South Wales and the Australian Capital Territory, and one of the threats they face is a disease familiar to anyone who has taken a comprehensive high school health class: chlamydia.

Chlamydia can cause infertility, weakness and blindness, as well as making koalas even more vulnerable to other dangers. It is a contagious disease that is transmitted through close contact, including mating. The magnitude of the impact depends on the wild population: some are completely saved and in others 90 percent of koalas are infected.

In 2025, the first chlamydia vaccine was approved for koalas, after more than a decade of work. As a follow-up, scientists have developed a vaccine implant that delivers two doses of the koala chlamydia vaccine in one go. He was given to the first wild koala on May 19.

“We have been working on chlamydia vaccines in koalas for over five years and this is a major breakthrough as we are converting a two-shot vaccine into an injection and implant that can be given in one exam,” Michael Pyne, wildlife veterinarian at Currumbin Wildlife Hospital, said in a statement. “It’s truly an extraordinary moment.”

The koala in question is an 18-month-old female nicknamed Bamse, which means teddy bear in Norwegian. She was taken from Burleigh Heads (a suburb on the east coast of Australia), sedated, vaccinated and given a vaccine implant at the Currumbin Wildlife Hospital in Currumbin, Australia, and released again. The implant should have ruptured 30 days later (sometime in June), releasing the second dose.

Since then, four more wild koalas at Burleigh Heads have received the implant. Two of them, including Bamse, were readmitted for their one-month follow-up. Fortunately, they are not yet infected with chlamydia.

The trial in wild koalas comes after the implant was successful in trials with koalas in captivity. If the implant is also effective for wild populations, it would provide a much more practical alternative to vaccinating wild koalas on a large scale than having to recapture them for the second dose.

“Bamse is 100% pioneering,” said Tanya Pritchard, a conservation scientist at the World Wildlife Fund. “When we look back at the history of koala conservation, this beautiful little koala may end up being one of the most important of this century.”

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