The iconic and endangered Koala has been devastated in recent years by both the destruction of their habitat, but also by the spread of Chlamydia. 

In humans, this is treated with antibiotics, but in Koalas this can disrupt their ability to digest eucalyptus leaves, their sole food source, leading to starvation.

Enter the University of Sunshine Coast, which has invented a vaccine that reduces the disease's mortality rate by "at least 65%"; the treatment was approved by regulators today.

https://abcnews.go.com/International/wireStory/australia-approves-world-vaccine-save-koalas-chlamydia-125500524

Some good news in the world!

Did chlamydia jump from humans to koalas or vice versa?

Australians:

Seriously though, Chlamydia is a bacteria that affects a wide range of animals, and apparently the strain affecting Koalas is most similar to one affecting sheep, so it may have infected them via livestock brought over by settlers:

https://www.science.org.au/curious/earth-environment/did-koalas-catch-killer-chlamydia-sheep

Reminds me of an old joke I used to hear

Q:What do you call a sheep tied to a pole in Australia?

A:A Playstation

If they would just practice safe sex!

Here in Aus we like to tease our neighbours in New Zealand about sheep; "what do you call a Kiwi with a lot of girlfriends? A shepherd."

On a more serious note, hopefully this does work, as Koala numbers have fallen by as much as 80% in the last two decades, with a 2020 report warning they may be extinct by 2050.