One Shot for the Koalas: Australia Okays First-ever Chlamydia Vaccine

Australia signed off on a world-first: a single-dose vaccine designed to protect koalas from chlamydia, a bacterial infection that’s been quietly wrecking the iconic marsupial—causing infertility, blindness, and, in too many cases, death.

Cleared by the national veterinary medicines regulator, the vaccine can now be used in wildlife hospitals, vet clinics, and in the field, with the first jabs aimed at the most vulnerable populations in Queensland and New South Wales, where infection rates often hover around 50% and can hit 70% in some colonies.

“This disease accounts for as much as half of koala deaths across all wild populations,” said Professor Peter Timms, who led the decade-long research effort at the University of the Sunshine Coast. “We knew a **single-dose vaccine—no booster—**was the answer to stopping the rapid, devastating spread.”

Field trials suggest the jab cuts the chance of breeding-age koalas developing symptoms and reduces mortality by at least 65% in the wild. That’s a big deal, not least because the standard treatment—antibiotics—often wrecks a koala’s gut flora, making it harder to digest their one-and-only food, eucalyptus leaves. Translation: treat the infection, risk starvation. The vaccine sidesteps that bind.

Koalas are listed as endangered in Queensland, NSW and the Australian Capital Territory. Numbers have fallen sharply over the past two decades thanks to a brutal combo of habitat loss (fire and development), road strikes, climate stress—and disease. A NSW government assessment in 2020 even warned koalas could vanish by 2050 without serious intervention.

Backers see the vaccine as a crucial plank in a broader rescue plan. The research has been supported by federal, NSW and Queensland governments. Federal Environment Minister Murray Watt pointed to Canberra’s AU$76 million Saving Koalas Fund, saying the disease is “a widespread threat impacting their reproductive health and causing infertility.”

Some conservationists are wary of what they call a “silver bullet” mindset. Deborah Tabart, chair of the Australian Koala Foundation, argues the priority should be stopping bulldozers, not starting mass inoculations.

“At the risk of sounding flippant, how can anyone be so delusional as to think that you can vaccinate 100,000 animals? It’s just ridiculous,” she said, adding, “I accept that chlamydia is an issue, but they’re sick because they haven’t got any habitat.”

The Queensland Conservation Council welcomed the vaccine but echoed the land-clearing alarm. Director Dave Copeman called the approval “really good news” that tackles one key stressor, but warned koalas “will remain at risk even if we manage chlamydia perfectly, because we keep on destroying their habitat.”

Because it’s single-shot, wildlife vets can vaccinate rescued koalas on admission or during routine health checks and release them without trying to recapture the same animal weeks later for a booster—logistically near-impossible in the bush. Expect early rollout to focus on hotspot regions, populations under intense disease pressure, and koalas already coming through clinical care.

The bigger picture

• Why chlamydia matters: In koalas, Chlamydia pecorum can cause urinary tract disease, infertility, eye infections leading to blindness, and death—undercutting reproduction just as habitat pressures mount.
• Why antibiotics don’t cut it: They can clear infection but disrupt gut microbes, risking malnutrition in an animal that lives on nutritionally poor leaves.
• Why this vaccine is different: A single dose that’s shown to reduce disease and deaths in the wild is practical, scalable and avoids the gut-flora trap.

Both camps are right about something. Vaccines won’t save koalas if trees keep falling. But habitat protection won’t save a population if chlamydia keeps sterilizing it. For a species under pressure from many fronts at once, success likely looks like doing all of it: lock in habitat, cool the climate risks, fix roadkill black spots, and deploy biomedical tools where they make a measurable difference.

Timms, for his part, frames the approval as a tool, not a cure-all:

“This is about protecting the nation’s most at-risk koalas,” he said.

The hard part now? Getting jabs where they’ll count the most—while the trees they live in are still standing.

AP and the Independent contributed to this report.