Since the current strain of highly-pathogenic avian influenza — H5N1 — began circulating in the country in February 2022, farmers across the country have lost or had to cull more than 58 million poultry birds. Photo by Getty Images.

By Adam Goldstein
Indiana Capital Chronicle

WASHINGTON — The deadliest outbreak of bird flu in U.S. history is prompting growing concern in Congress, and Department of Agriculture researchers are awaiting the preliminary results of four trials of vaccines for poultry.

While bird flu likely poses little health danger to humans, it’s contributed to spikes in U.S. egg prices and decimated poultry flocks. Among the domestic poultry affected are chickens, turkeys, pheasants, quail, ducks and geese — in both big commercial operations and increasingly popular backyard flocks.

The USDA estimates it has already spent more than $670 million in insurance indemnities and sanitation services to combat the ongoing bird flu outbreak.

The USDA is testing two proprietary vaccines developed through its Agricultural Research Service, as well as bird flu vaccines from pharmaceutical companies Merck Animal Health and Zoetis, Inc.

Jenny Lester Moffitt, undersecretary for marketing and regulatory programs at the USDA, said at an April 24 press event that it will take a minimum of 18 to 24 months to produce a viable vaccine, which is not guaranteed to be effective against infection.

Yuko Sato, a poultry veterinarian and associate professor at Iowa State University in Ames, Iowa, said at an April 26 media event that “the vaccine is not a silver bullet” for an end to the outbreak.

“You would have to make sure that if you vaccinate — but still have positive birds — you can stamp out the virus,” Sato said. “Otherwise, we’ll never be looking at eradicating the virus from the United States.”

Here are the answers to some common questions about the ongoing bird flu outbreak and potential vaccines:

What Is Highly-Pathogenic Avian Influenza?

Highly-pathogenic avian influenza, commonly known as HPAI, bird flu, or “high-path,” is a deadly respiratory virus that affects wild birds and poultry.

The contagious disease comes from the Influenza A family, and is characterized by the H5 or H7 categories of hemagglutinin — or spike protein — structures on its surface, which it uses to infect cells. The virus is spread via airborne transmission, or exposure to the byproducts of an infected bird, like saliva, mucus or feces.

Wild migratory birds are the primary transmission vector in the current outbreak, accounting for roughly 85% of disease spread, according to the USDA. These animals, including terns, ducks, and geese, can contract and pass along the disease without obvious physical symptoms.

Yet an HPAI infection spreads quickly among a flock of poultry, with infections leading to mortality at a rate of 90% to 100% in chickens and turkeys, often within 48 hours, according to the Animal and Plant Health Inspection Service.

When a farmer detects the disease in a commercial flock, the only USDA-recommended option is to kill the remaining birds, dispose of the carcasses, and decontaminate the facility to mitigate spread.

What About A Vaccine?

While some animal health experts say developing a vaccine for the current bird flu strain could be a valuable tool, trade experts caution that a national vaccination strategy would not come quickly, or without tradeoffs for the nation’s $6 billion poultry export industry. 

Sato said that a national vaccination strategy for the roughly 10 billion commercial-purpose birds in the United States could be time-intensive, and cost billions of taxpayer dollars.

Tom Super, senior vice president of communications at the National Chicken Council, said that his organization does not support the use of a vaccine for HPAI right now, as most countries do not accept exports from countries that vaccinate for the virus.

These non-tariff trade barriers are designed to protect other nations’ unvaccinated poultry flocks from immunized birds that still carry the disease. Super added that if the U.S. vaccinates domestic birds, the broiler industry will be cut off from exports, costing billions of dollars to the U.S. economy every year.

Tyler said that the Department of Agriculture’s Animal and Plant Health Inspection Service and Foreign Agricultural Service have made significant progress in developing regionalization agreements with foreign governments since 2015.

He noted that the U.S. poultry industry has managed roughly $11.7 billion in exports over the last two years, despite the ongoing challenges of HPAI and bans on poultry exports by certain countries like China.

Super and Tyler both advocated for continued funding for the Animal and Plant Health Inspection Service to provide rapid-response support to farms.

Moffitt urged adhering to biosecurity measures like interstate surveillance and the Defend the Flock program at the April 18 hearing. Moffitt cited that the number of infections in commercial flocks in March 2023 decreased tenfold compared to March 2022, proof the USDA’s current strategy of rapid tests and reporting is working.

“We know how to respond quickly, so producers can get back to producing food, how important biosecurity is, how to keep markets open,” she said. “We know what to do, and we are ready.”

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