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Australia starts chlamydia vaccine trial in koalas

Australia's University of the Sunshine Coast announced it is enrolling 400 koalas in a trial to see whether a vaccine can prevent infection.
A koala is vaccinated against chlamydia at the Australia Zoo Wildlife Hospital in Queensland, Australia, on Oct. 15, 2021.
A koala is vaccinated against chlamydia at the Australia Zoo Wildlife Hospital in Queensland, Australia, on Friday.University of the Sunshine Coast / Xinhua News Agency via Getty Images

Scientists at an Australian university hope to help make the island's dwindling and beloved koala population healthier with a chlamydia vaccine for the marsupials.

The University of the Sunshine Coast said this month that it had started the third phase of a clinical trial for an experimental vaccine.

Chlamydia can be deadly for the animals. It causes complications similar to those in humans if left untreated, including pinkeye, genital pain, discharge and cysts.

According to a 2019 study in the journal Scientific Reports, about half of the koalas in one geographic area of Australia tested positive for the infection, and many of those that tested positive were also infertile.

Since 2018, Australia has lost an estimated 30 percent of its koalas because of wildfires, drought, heat waves and land clearing, the Australian Koala Foundation said last month.

The vaccine has proven to be safe in the first two phases of the University of the Sunshine Coast's trials, Peter Timms, a professor of microbiology, said in a statement, adding that the study involved around 200 wild and captive koalas.

The next phase will involve 400 koalas, including those that live in sanctuaries, as well as animals that enter the hospital for treatment, he said.

They will be divided into two groups: 200 will get the single-shot vaccine, and 200 will be in a control group.

"While this vaccination will directly benefit each of the animals, the trial will also have a focus on the protection provided by vaccination," Timms said in a statement. "All koalas will be microchipped, and the hospital will record any animals that return for any reason over the following 12 months."

Timms said his team was working with vaccine manufacturers and government regulators to speed the release of a vaccine in case the trial results are positive.

A clinical trial is also underway in the U.S. for a human vaccine for chlamydia. A Phase 1 trial testing the safety and immunogenicity of a human chlamydia vaccine, which began in 2019, is expected to be complete next year, according to the National Institutes of Health.