One of the gravest threats to koalas, alongside habitat loss, dog attacks, and getting hit by cars, is chlamydia.

In many populations of the beloved marsupial, around 50 percent are infected; in the hardest hit groups, it’s as much as 70 percent.

The disease can lead to bladder inflammation, infertility, blindness, and starvation, and causes up to half the koala deaths in the wild.

Koalas contract it through bodily discharges, mating, and from an infected mother during birth. Babies, or joeys, are thought to also get it by eating pap, a form of feces their mothers produce that helps them digest toxic eucalyptus leaves.

Antibiotics alleviate symptoms, but they can also fatally disrupt koalas’ digestion and don’t prevent future infection. Now help is on the way: After 10 years of research trials led by Peter Timms, a microbiologist at the University of the Sunshine Coast, Australia’s veterinary medicine regulator has just approved a vaccine. The shot reduces the likelihood of infection and developing symptoms, preventing death in almost two-thirds of recipients. Timms believes the vaccine, once it’s rolled out in the coming years, will be “the single thing that could turn a population around.”