PORTLAND, Ore. (KOIN) — The Oregon Zoo is one of multiple organizations testing a new vaccine on California condors to protect the endangered birds from the deadly bird flu outbreak that killed more than 49 million wild and domesticated birds across the U.S. in 2022.

The vaccine trial for highly pathogenic avian influenza, the Oregon Zoo said, is the first of its kind for wild birds in the U.S. If successful, the vaccine will help protect the birds from the virus after it killed more than 20 endangered condors in the spring of 2022, Oregon Zoo Animal Health Director Carlos Sanchez said.

“The importance of finding a vaccine that’s effective in protecting California condors cannot be overstated,” Sanchez said. “This is a species that not long ago was on the very brink of extinction. Just over 300 individuals exist in the wild — and this year, in a matter of weeks, HPAI wiped out 21 of them. If left unchecked, the disease could undo decades of conservation work in the blink of an eye.”

Early clinical trial results released on Oct. 16 show that 60% of the vaccinated condors had a measurable number of antibodies, which is expected to protect them against the deadly disease. Other participants in the study include the U.S. Fish and Wildlife Service the Los Angeles Zoo and Botanical Gardens and the San Diego Zoo Wildlife Alliance.

In 2003, the Oregon Zoo partnered with the U.S. Fish and Wildlife Service’s condor recovery effort with the goal of “hatching and releasing as many condors as possible.” Since that time, the condor population ballooned to 500, with more than 300 condors existing in the wild. In 2022, the zoo hatched a record 12 condor chicks. The zoo also released eight condors into the wild, including the three birds used for the Yurok Tribe’s historic reintroduction in Humboldt County, Calif.