Jet, a young Asian elephant at the St. Louis Zoo, has received an experimental mRNA vaccine designed to protect young elephants from a potentially deadly virus.
Jet, who is 1 ½ years old, is the first elephant at the zoo to receive the vaccine and is among the first Asian elephant calves in the world to get the treatment, zoo officials said in a statement.
He received his third and final dose of the vaccination series on Sept. 30 and is doing well, according to the zoo.
The vaccine targets elephant endotheliotropic herpesvirus, a viral disease that is dangerous for young Asian elephants. Calves are especially vulnerable, with reported mortality rates of 60% to 80%.
"This vaccination is a critical step forward in the decades-long effort to protect Asian elephants from EEHV," said Dr. Kari Musgrave, the zoo's director of animal health, in a statement.
The vaccine was developed by virologists at Baylor College of Medicine, which has worked with elephant veterinarians and researchers for years to develop new ways to fight EEHV. Researchers began developing the mRNA vaccine in 2009, and adult elephants at the Houston Zoo received the first doses in 2024.
For the St. Louis Zoo, Jet's vaccination carries a particular significance.
In 2018, Kenzi, a 6-year-old Asian elephant at the zoo, died of EEHV. She is the only elephant at the zoo to have died from the disease.
"Our team understands just how devastating EEHV can be," said Katie Pilgram-Kloppe, curator of Ungulates and River's Edge, in a statement. "I can't describe how it feels to know that Jet has an extra layer of protection against the virus that has threatened his species for decades."
Jet still has antibodies passed from his mother, Jade, that protect against EEHV. Those are expected to decline over the next couple of years, making the vaccine an additional source of protection while Jet's own immune system develops its response to the virus.
Zoo veterinarians will monitor Jet closely, including regular blood tests, to measure his antibody levels after vaccination.
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