Houston-developed elephant vaccine reaches milestone

Threat level: EEHV is the leading cause of death among juvenile Asian elephants in North American zoos and remains a threat to elephant calves across Asia.

Flashback: The two organizations have been collaborating for 15 years after a young Houston Zoo elephant died from EEHV.

• In June 2024, Houston Zoo's Asian elephant Tess became the first elephant ever to receive the experimental EEHV mRNA vaccine. Since then, several other elephants have received the vaccine. Jeroen Pollet of Texas Children's Hospital also helped produce the first vaccine batch.

What they found: One study published in the Journal of Virology tested the vaccine in nine Asian elephants at five zoos, including Houston Zoo. Researchers found it safely produced EEHV antibodies that lasted for months, showing the vaccine successfully trained elephants' immune systems.

• The other study, also in the Journal of Virology, followed two vaccinated juvenile elephants at the Cincinnati Zoo after they naturally contracted EEHV1A. Both stayed healthy, requiring no medical treatment and recovering without developing hemorrhagic disease, providing the first evidence the vaccine may protect against severe illness.

What they're saying: Lisa Peterson, president and CEO of Houston Zoo, said in an announcement that the findings "offer real hope and bring us one step closer to changing the future for elephants."

What we're watching: Researchers are already developing next-generation EEHV vaccines for Asian elephants and exploring vaccines for African elephants.