Bird flu threatens chickens. Why farmers don’t want a vaccine.

Bird flu, which last made major waves in the US poultry industry in 2014 and 2015, is back. The current strain, known as H5N1, has ravaged US chicken coops since early last year, causing infections in more than 800 poultry flocks and killing nearly 60 million chickens and chickens. other birds (about 10 million more than in the last round of infections). For U.S. consumers, the impact was felt in the grocery aisle, the average price of eggs more than doubled since early 2022.

From an industry perspective, the impact has been relatively limited, at least so far. The majority of exterminated birds belonged to large private commercial egg farms.

Cal Maine Foods

(ticker: CALM), the largest egg producer in the United States, says its farms have not been affected. (In fact, the company is having a record year, posting quarterly earnings of $6.62 per diluted share in March, compared to $0.81 in the same quarter last year, an improvement due in part to higher stock prices. eggs and demand.) Chickens raised for meat, called broilers, were largely spared.

Soaring egg prices – and concerns about allowing a virus, which has in very rare cases passed from birds to humans, to take hold – has sparked debate over whether United States should adopt an H5N1 poultry vaccination campaign. At this point, such a move seems remote at best. Despite Press articles early March that the Biden administration is considering a vaccination effort, a White House National Security Council spokesperson said barrons, “Right now, we are focused on promoting and improving high-impact biosecurity practices and procedures.”

But the full impact of H5N1, which scientists say may already be endemic in US bird populations — meaning it will reappear on a regular basis — remains to be seen. If the virus persists, hits hard this spring, and perhaps begins to affect even more birds, the pressure to vaccinate could quickly escalate. This would have significant implications for producers of chickens and other birds, not to mention the animal health actors who manufacture and distribute the vaccines.

“Once it gets to that endemic stage, it just makes sense to vaccinate,” says Dr. Carol Cardona, a professor in the Department of Veterinary and Biomedical Sciences at the University of Minnesota. “Once you realize it’s going to come back and come back and come back, the cost of treating it like an epidemic every time, like something you can eradicate, becomes less appealing.”

The decision to vaccinate American birds could face several obstacles, including the fact that most of the poultry industry would oppose it. The United States is one of the largest poultry exporters in the world; the country exported $6 billion worth of poultry meat in 2022. Producers fear other countries will stop importing U.S. chicken meat over fears vaccination will mask infections.

These concerns come from experience. In 2014 and 2015, when an earlier H5N1 strain forced farmers to exterminate 50 million birds, the majority of which were turkeys and laying hens, more than 50 countries imposed trade restrictions on all US poultry. Chicken meat exports fell by $1.1 billion in 2015, according to a United States Department of Agriculture reporteven though the virus has almost entirely spared broiler flocks.

So far, the United States has been successful in persuading its trading partners not to impose these kinds of sweeping bans during the current outbreak. (Some countries have imposed import restrictions at the county or state level.) But given that no other major poultry exporter has its birds vaccinated against H5N1, choosing to go this route would almost certainly result in pushback from importers.

If the government were to decide that some level of vaccination against H5N1 was necessary, the next challenge would be to protect birds against the current strain of the virus. The USDA is set to begin an avian flu vaccine trial this month, with initial data available in May and full data from a two-dose challenge trial in June. A USDA spokesperson said the agency would test four candidate vaccines. An official of the animal health society

Zoetis

(ZTS) says one is an H5N1 vaccine the company developed in 2015; details of the other three candidates have not been released.

If one or more of the vaccines are effective, the USDA spokesperson said the agency would find manufacturers willing to produce them and go through the process to get them approved, which can take up to three years. but in “emergency situations”. it could be accelerated.

Zoetis says it is currently working to determine the effectiveness of the vaccine currently being tested by the USDA against the current strain. Another bird flu vaccine Zoetis, which targets a different strain, is used in countries such as Egypt, Jordan and Iraq.

Outside the United States, Dutch scientists said in mid-March, tests of Ceva’s bird flu vaccine and a vaccine from German private pharmaceutical company Boehringer Ingelheim found both to be “100% effective in preventing disease and death” in a small number of laying hens after H5N1 infection.

Ceva’s vaccine is not specific to H5N1 but targets all H5 viruses. “We have an effective vaccine,” says John El-Attrache, global director of science and investigation at Ceva. “It’s available.”

If US authorities decide on a vaccine, the next question would be which birds to vaccinate. Turkeys used for breeding are a likely choice; they have been particularly susceptible to the virus, and there are relatively few of them. Among chickens, the likely targets would be laying hens, as they live longer and are more susceptible to infection than broilers.

Layers are usually vaccinated against other diseases as chicks; a campaign targeting mature birds would be a complicated undertaking, Cardona says. “Every time a person enters a barn, there is a risk (of transmission of infection),” she says. So rather than vaccinating adult chickens, Cardona advocates inoculating young chicks before they are brought to the facility where they lay eggs. This would make achieving a fully vaccinated secular farm a two or three year process.

Another potential complication is that some of the bird flu vaccines, including Ceva’s, are constructed using a live turkey herpes virus. This same skeleton is used in other vaccines that have already been given to many chickens, but an individual chicken can only receive one turkey herpesvirus vaccine. If Ceva’s vaccine were to be given to US chickens, another vaccine would have to be replaced with an alternative.

For vaccine makers, an H5N1 vaccination campaign is unlikely to have significant revenue implications, given that vaccines for chickens can cost less than a penny per dose. “This is not an opportunity for an animal health company that is going to change the revenue trajectory of the business,” says Kristin Peck, CEO of Zoetis. “We will do it because it’s the right thing to do.”

Yet animal health companies are not ignoring the opportunity. Besides Zoetis, Ceva and Boehringer Ingelheim,

Merck

(MRK) also said its animal health division has an “extensive and ongoing research program” focused on avian influenza.

For now, the issue of vaccination remains unresolved. During a March 16 Senate hearing, USDA Secretary Tom Vilsack told lawmakers not to expect an answer any time soon. “We are far from having an effective vaccine and far from having a vaccine accepted by the rest of the world,” he said.

For scientists, however, this spring – a season when bird flu usually breaks out – will be an important test.

Cardona says, “When I look at the situation, I think we need to look at vaccination.”

Write to Josh Nathan-Kazis at [email protected]