FILE PHOTO: A person holds a test tube labelled "Bird Flu" next to eggs, in this picture illustration, January 14, 2023. REUTERS/Dado Ruvic/Illustration/File Photo
FILE PHOTO: A researcher uses a pipette to transfer a sample into a microtube during a press visit, as researchers work to monitor and prevent the spread of avian influenza, including the H7N9 bird flu virus, at the Institut Pasteur in Paris, France, November 24, 2025. REUTERS/Gonzalo Fuentes/File Photo
FILE PHOTO: Duck carcasses are disposed of at a duck farm in Neuhardenberg, following the outbreak of the highly contagious bird flu among cranes at a gathering place for migratory birds, in the federal state of Brandenburg, Germany, October 26, 2025. REUTERS/Christian Mang/File Photo

By Leah Douglas

WASHINGTON, Dec 11 (Reuters) - A bipartisan group of U.S. senators this week urged the administration of President Donald Trump to finalize a science-based plan for developing a bird flu vaccine for livestock, according to a letter seen by Reuters.

More than 180 million chickens, turkeys and other poultry have been killed due to an outbreak of bird flu that began in 2022. The U.S. Department of Agriculture said in June that it was developing a potential poultry vaccination plan, but has not released further details.

The USDA should take "renewed action" to fight bird flu as infections rise during the winter months, said 23 U.S. senators in a letter sent on Wednesday to Agriculture Secretary Brooke Rollins and reported first by Reuters.

"Any finalized vaccine strategy must take into account feedback from animal health stakeholders, industry experts, and be grounded in sound science," said the letter, led by Amy Klobuchar of Minnesota, the top Democrat on the Senate Agriculture Committee, and Republican U.S. Senator Mike Rounds of South Dakota.

Other signatories to the letter include Senate Majority Leader John Thune of South Dakota and several Republican and Democratic members of the Senate Agriculture Committee.

A USDA spokesperson said farmer biosecurity efforts are the most effective tool for mitigating the spread of bird flu and that the agency's response to the virus "is grounded in decades of scientifically validated epidemiological practices and biosecurity protocols."

In March, the USDA pledged $100 million to research vaccines and therapeutics for egg-laying chickens as part of a broader strategy to fight bird flu, which had driven egg prices to record highs.

The agency said in June it had received 417 proposals for the funds, but has not announced further details.

The Trump administration in May canceled a $700 million contract with Moderna to develop a human bird flu vaccine. Health Secretary Robert F. Kennedy Jr., a longtime anti-vaccine activist, has cut other funding for vaccine research and scrapped long-held federal vaccine guidance.

The poultry industry is divided on vaccination because of the potential to hurt exports. The senators urged Rollins in their letter to "work closely with trading partners and impacted producers to fully assess and manage any potential trade implications" of a vaccine plan.

The USDA told Reuters in late November that the agency had not shared a plan for poultry vaccination with trading partners.

(Reporting by Leah Douglas in Washington; additional reporting by Tom Polansek in Chicago; Editing by Bill Berkrot and David Gregorio)