Last week, under newly appointed Secretary Brooke Rollins, the USDA granted a conditional license to Zoetis' avian influenza vaccines for use in chickens.
According to Zoetis, USDA's Center for Veterinary Biology (CVB) has issued a license based on blood tests that measure the safety, purity and immune response of the vaccine, as demonstrated through serology data. did.
However, this is a conditional license. The vaccine is officially dubbed the “Avian Influenza Vaccine, H5N2 Subtype, and the Virus Killed,” but has yet to undergo a full-scale field trial to prove its long-term efficacy. Conditional approvals limit vaccine use in emergencies.
On February 8, 2022, the USDA declared an emergency response to the outbreak of highly pathogenic avian influenza (HPAI).
Moving from culling to vaccination
For years, USDA has relied on mass culling as a major response to HPAI outbreaks. As of the latest update from the USDA, the Centers for Disease Control and Prevention (CDC) has cited since over 160 million birds were affected in February 2022.
The exact number of birds that were culled is not specified. However, ulling is the standard response to HPAI outbreaks to control and contain viruses. This means that a significant portion of the affected birds have been slaughtered.
The Trump administration's decision to approve the Zoetis vaccine shows a pivot in the federal response.
Kevin Hassett, director of the National Economic Council, is working with the USDA on this response. As he told Face The Nation, the new plan will focus on “biosecurity and medication” and methods of target containment.
Why farmers avoid vaccinating chickens
Culling is widely regarded as an inefficient measure as wild birds such as Mallard ducks continue to reinfect their chickens.
Vaccines do not rule out this risk, and raise new concerns.
The avian flu vaccine has been available for years. However, American farmers have largely avoided using them. The reasons were a combination of trade restrictions, logistical challenges, and concerns about viral mutations and interspecies transmission. Vaccines are the standard tool in the fight against poultry disease. However, HPAI vaccinations are controversial and rarely implemented on a large scale.
Trade barriers and export concerns
One of the biggest reasons why poultry farmers in the United States have avoided vaccination is international trade policy. Many countries, including China and the European Union, have banned the import of poultry from countries that correspond to avian flu. The concern is that vaccinated birds can still carry and spread the virus asymptomatically. This makes it difficult to detect and control outbreaks. If the US poultry industry adopts vaccinations widely, it risks losing access to billions of dollars in export revenue.
The US broiler industry plays a major role in the global poultry market, exporting much of its production every year. Between 2013 and 2022, approximately 17% of US chicken production was sent to other countries, making it the most export-centric poultry product.
In 2024, US poultry exports (excluding eggs) were worth around $5.53 billion, an average of $5.666 billion over the past three years. This highlights how much the industry relies on international trade and how important exports are to economic success.
Logistics and Cost Barriers
Most avian flu vaccines require separate injections, making them unrealistic on large poultry farms in the United States. There, the flock can count numbers with dozens or hundreds of thousands of birds. Unlike Newcastle disease and infectious bronchitis vaccines that can be administered through sprays and drinking water, the avian flu vaccine requires a practical workforce for each bird, significantly increasing time, cost and logistical challenges .
For farmers, this presents a huge financial burden. This is because vaccinating the entire flock requires additional labor, specialized equipment, and significant operational adjustments. As a result, most poultry producers hesitated to invest in vaccination programs without making particularly strong incentives or changes to trade policy, and without making it a viable alternative.
Possibility to drive mutations
Partial vaccinations of only some herds can lead to new resistant strains of avian influenza. If only a portion of the bird is vaccinated, the virus continues to circulate in unvaccinated birds, and even infects partially protected vaccinated birds, causing the virus to adapt and evolve. I'll force it. This process makes it difficult for strains that can bypass immunity to survive, spread, and control future outbreaks.
If the vaccine is 100% ineffective, the risk increases dramatically. This is a scenario known as a “leaky” vaccine. Unlike sterile vaccines that completely block infections, leaky vaccines reduce symptoms, but do not stop viral infections. This means that infected but asymptomatic birds can continue to spread the virus, allowing the mutation to remain unaware. Scientists have observed this phenomenon in other poultry diseases, such as Marek's disease, where leaky vaccinations contributed to the emergence of more toxic and deadly strains.
A similar pattern occurs with the infamous, low-efficiency seasonal influenza and Covid-19 vaccines. These require constant updates to keep up with new mutations that avoid previous immunity, and in many cases, previous doses are ineffective.
Jump species
A new concern is that recent avian flu variants have begun to infect dairy cows. For example, the D1.1 strain of H5N1 affects US dairy cows, resulting in lower milk production and other issues. This suggests that the virus is adapted to mammals and may ultimately increase its ability to infect humans. The more the virus circulates and mutates, the greater the risk of a strain that can be transmitted from human to human.
It should be emphasized that many chickens survive the virus, develop innate immunity, and both culling and vaccination are unnecessary.
Next: Avian flu vaccines for humans?
In parallel with this, Modanya is developing a new mRNA-based vaccine to combat human avian influenza. On the last day of Biden's term, the company received a $590 million grant from the Department of Health and Human Services (HHS) to accelerate the development of a pandemic flu vaccine, including those targeting avian flu strains. Ta. The initiative aims to prevent potential ripple infections from animals to humans by leveraging the same mRNA technology used in the Covid vaccine, which HHS described as “successful” in a press release. Masu.
As New American reported last June, Western countries, including the United States, view avian flu as a serious pandemic threat due to its potential mutations. And they see vaccinations as an important component of their “pre-pandemic” preparatory plan.
With Robert F. Kennedy Jr. currently leading the HHS, it remains to be seen whether this strategy will change. It may be adjusted or cancelled. This concern comes from the influence of biotech investor Jim O'Neill, Kennedy's deputy and major operational lead. His stance can either create tension within the department or lead the policy quietly in a direction that is at odds with Kennedy's stated commitment to more stringent surveillance.
Additionally, longtime Biodefense insider Gerald Parker will lead the White House office's Pandemic Response and Response Policy (OPPR). As Dr. Robert Malone documented, Parker's role in OPPR centers on shaping the US response to avian flu and future pandemics, with his pro-vaccine biosecurity-heavy approach Issues warning about federal policy alignment.
