By Malinda Larkin and R. Scott Nolen
More than 168 million poultry in the U.S. have been affected with highly pathogenic avian influenza (HPAI, more specifically avian influenza type A H5N1) since February 2022, including in backyard and commercial flocks, according to the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS).
In late February, Ag Secretary Brooke Rollins announced a five-pronged, $1 billion approach to combat avian flu and reduce egg prices, including efforts to explore vaccine use, therapeutics, and other strategies to protect poultry and reduce depopulation. Then the USDA, under the Trump administration, held its first call on March 11 with state officials and industry stakeholders to discuss surveillance, potential therapeutics and vaccination strategy, and logistics.
On March 20, the USDA, in consultation with the U.S. Department of Health and Human Services (HHS), the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the Food and Drug Administration (FDA) announced initial plans for a funding opportunity to explore prevention, therapeutics, research, and potential vaccine candidates. The USDA will invest up to $100 million in these projects, which it hopes will identify and foster innovative solutions to fight H5N1 and directly support America’s farmers and ranchers.
The notice of funding opportunity, including application instructions and additional information, is available on the APHIS website. Applicants can also find information on grants.gov by searching for “USDA-APHIS-10025-VSSP0000-25-0015.” Researchers have until May 19 to submit applications.
Biosecurity challenges
Half the USDA’s $1 billion strategy for combating H5N1 is allocated for biosecurity assessments and audits at commercial poultry operations unaffected by the virus. These federal reviews include methods for preventing contact with potentially infected wildlife and helping producers identify and rectify biosecurity gaps in their operations.
APHIS has prioritized assessments at egg-laying facilities in the highest-egg producing states such as Iowa and Ohio as part of the Trump administration’s promise to lower egg prices.
Dr. Michelle Kromm, a veterinarian with 15 year's experience working commercial turkey operations, agrees that robust biosecurity measures can greatly reduce the risk of disease introduction at poultry operations. Those measures are not fool proof and can be overwhelmed by a large dose of the virus.
Safety measures for protecting poultry flocks from H5N1 and other diseases are designed to stepwise reduce the level of pathogen load introduced in the barn, explained Dr. Kromm, a co-chair of the American Association of Avian Pathologists H5 Influenza Task Force. Low to moderate virus levels can be effectively addressed by intensive biosecurity, she continued, but high virus levels are difficult to manage with biosecurity alone.
“Data from the current outbreak demonstrates that farmers have done a great job protecting themselves from their neighbors,” she said. “A vaccine would augment biosecurity by increasing the infectious dose for HPAI as well as decreasing the amount of virus that is shed by infected birds.
“The second part is what’s critical for containing outbreaks—especially if the current administration is looking to move away from the USDA policy of depopulating all the birds on an infected premise.”
Other species
While the USDA’s five-pronged approach has a clear focus on poultry, it’s broadly recognized that control of avian influenza means addressing it in other species as well. Multiple USDA agencies, including APHIS, Food Safety and Inspection Service (FSIS), and the National Institute of Food and Agriculture (NIFA), have been working in coordination with stakeholders to learn as much as possible about H5N1 virus transmission and risk factors within herds, between herds, and between dairy and poultry premises. They have also, according to the announcement, been looking at infections and pathogenesis in poultry, dairy cattle, small ruminants, and swine.
Species affected by H5N1 each have unique biosecurity issues.
Dr. K. Fred Gingrich II, executive director of the American Association of Bovine Practitioners, noted that poultry and swine are raised in enclosed barns: The animals arrive and leave together. Workers can decontaminate before and after visiting the barns, which have limited visitor access. That’s not the case with dairy barns.
“We ship animals on and off the dairy frequently. There are multiple shared service providers that visit multiple dairies every day: feed truck driver, nutritionist, hoof trimmer, breeders, employees, you name it,” he said. “We can enhance biosecurity, but because of the nature of our business, that provides opportunity for H5N1 to spread.”
The virus has been confirmed in 1,021 dairy cattle herds in 17 states as of mid-April. Another confounding factor is wild birds.
“We can’t keep birds away from cows. You go to any dairy and there are bird droppings everywhere. They get in the feed, in the stalls, and water,” Dr. Gingrich said. “We do our best to control birds on a dairy, but you can’t stop them … Now, there’s yet another hole that we have to plug.”
Vaccination
Dr. Gingrich says he’s supportive of a safe and effective vaccine, suggesting it will “highly likely be “critical in managing and eliminating avian influenza from the U.S. dairy herd. … Every year, we will bring in 30% naïve animals,” meaning that even if H5N1 is circulating on a low level, it could still affect a sizable portion of herds every year.
But he acknowledges that the conversation around vaccinating cows is different than that around vaccinating, for example, broiler chickens. Chickens are typically slaughtered at 6 weeks old compared to dairy cows that have an average productive lifespan of between 2.5 and 4 years. The economic value of both animals varies considerably, which factors in these decisions.
Since the 2014-15 outbreak of HPAI in poultry, the USDA has maintained the option to deploy vaccines in poultry, if needed. While deploying a vaccine for poultry would be difficult in practice and may have trade implications, the USDA has continued to support research and development in avian vaccines.
Currently, four vaccines are licensed by the USDA’s CVB for use in U.S. poultry for avian influenza—HA subtype, H5N1, H5N3, and H5N9—but none are approved for the more virulent strain, H5N1 clade 2.3.4.4b, spreading across North America.
In 2023, researchers at the USDA’s Agricultural Research Service (ARS) began testing whether any of the previously licensed bird flu vaccines could prove effective against the current strain. ARS investigators have also been researching H5 HPAI vaccines for cattle, swine, and other livestock, according to an October 2024 ARS announcement .
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