Koala Gets New 2-Shot Chlamydia Vaccine in World First

Bamse the koala made history in May when she received a revolutionary vaccine that could turn the tide for Australia's struggling koala population.

The 18-month-old female was captured near Burleigh, Queensland, given a vaccine injection paired with a biodegradable implant, then returned home the same day wearing a GPS collar. That implant releases the second dose over 30 days, solving a problem that has held back large-scale vaccination efforts for years.

"Bamse was a great candidate, a young female koala, the poster child for the future of the species," says Dr. Michael Pyne, Senior Vet at Currumbin Wildlife Hospital. "It's truly a remarkable moment."

The challenge until now has been getting wild koalas back for their booster shot four weeks after the first injection. Koalas are notoriously shy, and tracking down hundreds of individuals twice puts enormous stress on the animals and stretches resources thin.

Queensland University of Technology scientists created the implant to break down naturally while delivering the second dose, turning what was once a logistical nightmare into a single appointment.

Chlamydia might sound like a punchline, but it's killing koalas. Around 50% of Australia's remaining koalas carry the disease, with some populations hitting 90% infection rates. The bacteria can cause blindness and infertility, devastating a species already pushed toward extinction by habitat loss.

Female infertility is especially dangerous for isolated koala groups scattered along Australia's eastern coast. When populations get too small and fragmented, they can crash past the point of recovery.

The Ripple Effect

The vaccine is already working. In 2020, more than 70% of koalas from one southern Queensland population arrived at Currumbin Wildlife Hospital with chlamydia. Today, infection has dropped 75%.

More than 500 koalas have now received at least one vaccine dose at Currumbin and the Moggill Koala Rehabilitation Centre. The results include 41 joeys and 13 grand-joeys born into a community that was struggling to reproduce.

Since Bamse's treatment, four more koalas have received the injection-implant combo and returned to the wild. When Bamse and another koala were recaptured after a month for checkups, both remained chlamydia-free.

Dr. Pyne hopes to roll out the vaccine to at-risk populations across Australia's east coast. "We've seen such devastation from chlamydial disease in koalas in South East Queensland and New South Wales," he says. "But the progress we've made is truly exciting. It gives us hope and allows us to think there is a way to save koalas."