At the 2024 Farm Progress Show held August 27–29 in Boone, Iowa, U.S. Department of Agriculture (USDA) Secretary Tom Vilsack revealed that the agency is beginning field trials for a vaccine to address the ongoing outbreak of Highly Pathogenic Avian Influenza (HPAI) H5N1—also known as “bird flu”—in cattle.

According to Mr. Vilsack, numerous private companies have been working on the development of a vaccine, and very recently, one such company was approved to begin field trials. The trial will enable USDA to determine whether the vaccine is fit for commercial use.

The vaccine efforts are being overseen by USDA’s Center for Veterinary Biologics (CVB), which posted a notice on August 28 announcing that it is accepting submissions for field studies to support licensure of nonviable, non-replicating H5N1 vaccines that may be conducted outside of containment without terminal disposal of milk and other commodities. Previously, CVB indicated that all studies, even those not involving virus challenge, were to be conducted in containment facilities regardless of risk profile.

Mr. Vilsack’s announcement follows a letter written to him in early August, penned by several dairy and egg industry stakeholder groups, which urged USDA to “support the development of safe and effective H5Nx vaccinations for dairy cows, turkeys, and egg-laying hens.” The letter was signed by representatives from the International Dairy Foods Association (IDFA), the National Milk Producers Federation, United Egg Producers, and the National Turkey Federation.

Current Scope and Understanding of the Outbreak

As of August 30, the U.S. Centers for Disease Control and Prevention (CDC) has confirmed 193 cases of HPAI H5N1 in cattle across 13 states. In just the last 30 days, 18 cases have been recorded in five states.

The announcement about vaccine field trials beginning is the latest federal effort to curb the ongoing outbreak in dairy cattle. In recent months, USDA also revealed that it will begin testing dairy cows at slaughter for the presence of HPAI H5N1.

USDA and the U.S. Food and Drug Administration (FDA) have also been collaborating on several research initiatives to better understand HPAI H5N1, including the characteristics of inactivation methods for the virus in dairy products, the safety of dairy products at retail, and possible One Health interventions for the virus. So far, results have shown that pasteurized milk on sale at retail are safe, and that pasteurization is effective in inactivating HPAI H5N1 in dairy products.