A groundbreaking chlamydia vaccine to fight the decline of koala populations offers hope for a struggling species. Now listed as endangered in eastern Australia, koalas are beset by disease and habitat destruction and are clinging on for survival in many regions. With about half the koala population infected with chlamydia in Queensland and NSW, the single-dose vaccine offers a valuable tool for fighting the further spread of the disease.
After Phase III trials demonstrated a 64 per cent reduction in one koala population’s levels of chlamydia, alongside higher rates of reproduction, the vaccine was given regulatory approval in 2025.
Microbiologist Peter Timms from the University of the Sunshine Coast has spent more than 10 years developing the vaccine, determining the best ways for it to be deployed, and trying to scrape together funding from public and private sector donors.
Chlamydia disease can damage koalas’ eyes and even blind them. The disease can also cause cysts and damage the female reproductive tract, leaving the animals infertile. Chlamydia can be treated with antibiotics, but fewer than half of the infected koalas dosed with the drugs survive, Timms says, partly because the antibiotics can inhibit their ability to properly digest eucalyptus leaves.
“In some areas, chlamydia disease is the tipping point for koala populations,” he adds, because many large koala groups have already been disrupted by drought, floods, bushfires and habitat destruction for road and housing construction.
Timms and his colleagues and students have been involved in projects assessing various koala populations’ health and potential effects of habitat disturbance. They are then able to vaccinate the koalas in these wild populations.
The vaccine will potentially reduce the severity of chlamydia’s symptoms when a koala does contract the disease, and for koalas that are already infected it might reduce the future impact on the animal. “It should help female koalas and so help the population’s reproductive levels go up,” Timms says. “The vaccination is not the solution to everything, but it’s one of the management tools that can be a benefit.”
Professor Peter Timms has developed a groundbreaking chlamydia vaccine to combat the rapid decline of koala populations.
Deploying a vaccination regime can also be difficult. Koalas often live at the top of tall trees, so it’s not easy to give them subcutaneous vaccination injections, especially since funding has been hard to come by. “At the moment, our main thinking is that thousands and thousands of koalas come into wildlife hospitals already, so it’s pretty easy for that group of koalas to get vaccinated,” he adds.
The vaccine is thought to provide a good immune response in koalas for at least eight years, and potentially for much longer.
“It’s hard to do the long-lasting studies, because it’s super-expensive and we can only really tag on to studies that somebody else is doing,” Timms says.
Funding is always a problem, he adds. “Some of the vaccine ingredients have to be sourced from overseas, at a very high standard, costing ridiculous amounts of money.”
Many generous donors have helped but the work is expensive.
Timms and his colleagues have attempted to negotiate with governments, and tried to get research grants, but the support is never enough. He estimates about $1m is now needed to roll out the vaccine to more at-risk koalas.
“It’s not a simple process,” he says. “While we have achieved a major milestone with regulator approval, fully rolling out the approved vaccine is still some way off.”