Koala vaccine approval could pause slide in numbers

Chlamydia, a bacterial infection best known as a sexually transmitted disease in people, has increased the risk of koalas going extinct. Now, the approval of the first-ever vaccine to protect the iconic Australian bear-like marsupial from chlamydia promises to arrest a rapid decline in their numbers.

The vaccine also is regarded by scientists as a potential blueprint for treating chlamydia in other animals, such as sheep, cattle and humans.

This story was published on Sept. 16, 2025.