The U.S. Department of Agriculture on Friday granted animal vaccine company Zoetis a conditional license to use an updated vaccine targeting avian flu in chickens, the company said. The vaccine comes while egg prices have soared amid growing concern about avian flu.

How long has this vaccine been in the works? Researchers at Zoetis began working on the new vaccine in February 2022, the company said. A new strain of avian influenza appeared in the United States at that time and has since affected more than 150 million birds.

What is a conditional license? A conditional license is a temporary authorization for a company to distribute a vaccine, according to a USDA explainer document. During the time window when the company is distributing the vaccine, data is collected to ensure the vaccine is safe and effective. If the findings are favorable, the USDA could grant another conditional license.

Has Zoetis developed vaccines before? Zoetis has developed avian flu vaccines since 2001 when an avian influenza outbreak occurred in Southeast Asia, the company said. In 2016, the company received a conditional license from the USDA for an avian flu vaccine. It was also awarded a contract to fill the agency’s veterinary stockpile with the product.

This story originally appeared in WORLD. © 2025, reprinted with permission. All rights reserved.