Agriculture officials in the Biden Administration are testing four vaccines in hopes of stanching the latest outbreak of a highly pathogenic avian influenza that has devastated U.S. poultry farms and driven up egg prices, with plans to launch a national vaccination campaign that, if implemented, would be the first-ever effort of its kind.
Acccording to the Associated Press (AP), two of the vaccines being tested by the U.S. Department of Agriculture were developed by that agency. The others, from animal drugmaker Zoetis and Merck Animal Health, were developed during the last large-scale outbreak in 2015 and not used, a USDA spokesman said.
Should the trials be successful, the next stage is identifying manufacturers, with many more steps before laying hens, domesticated turkeys and broilers are vaccinated. In a best-case scenario, the agency estimates an 18- to 24-month timeline before having a commercial quantity of vaccine available that matches the currently circulating virus strain, but the timeline could be expedited in an emergency.
Although there is little concern that the virus, known as H5N1 avian flu, could spark a human pandemic, it has become a major headache for the world’s poultry farmers. This has been the largest and most deadly outbreak ever. Nearly 60 million farm-raised birds in the United States have died or been killed to stop the virus’s spread. The virus has also contributed to sky-high egg prices. But while “eggflation” has calmed temporarily, bird flu has not flown the coop.
Historically, avian flu outbreaks have come and gone. The virus went undetected in the United States for several years but reemerged in 2022 and has been present in North America ever since. But what is often a seasonal problem, peaking in spring and summer months with the movement of wild migratory birds, now seems not to be going away.
Experts say there are indications that the current aggressive strain may have become permanent in North America, part of a new normal to which the poultry industry must adapt.
The virus spread last year from the Atlantic Coast westward, Nichola Hill, a professor in the biology department at the University of Massachusetts at Boston, said in a briefing last week. It’s now been detected in 49 states, with Hawaii the one exception, according to the USDA. “So, we’ve seen continuous circulation in North America since that time, and it’s raised the question of whether this virus is now endemic,” she said.
Despite efforts to contain the virus, it has continued to spread among bird species and recently jumped to mammals. There have been no documented cases of human-to-human transmission, and people known to have been sickened worked closely with poultry. But it poses dangers for pets and means more uncertainty ahead for the cost of eggs.
As Reuters reports, Egg prices fell by almost 11 percent last month according to government data. Seth Meyer, chief economist for the USDA, optimistically predicted in February that wholesale egg prices would fall even further and total egg production would increase this year. But this prediction assumes there will not be continued avian flu outbreaks. And this, say many veterinarians and poultry experts, is wishful thinking.
Egg prices overall had been trending upward in the United States since the current strain of avian flu struck, increasing by 155 percent between the beginning of 2022 and the start of this year. Eggs became the go-to example as food prices rose more broadly, surging to $4.25 per dozen in December, which put pressure on Americans’ pocketbooks and drove up the cost of foods that contain eggs. Some people frustrated with the spiraling prices went so far as to decorate potatoes this Easter.
Analysts at Rabobank, a financial services provider, predict egg prices will remain elevated globally, with even higher prices in countries where strong avian flu pressures persist. Persistently high prices and scarcity could pose a particular challenge for low-income consumers because eggs are an important staple food, high in protein and nutrients.
More than 254 million birds have died of it or been depopulated worldwide, said David Swayne, a poultry veterinarian who specializes in avian flu, on a recent call with reporters. It is now considered a “panzootic,” meaning a pandemic in wild animals: Last month 3,500 sea lions succumbed to it in Peru, according to Peru’s national parks service. Scientists have detected the virus in more than 100 species of wild birds and the Centers for Disease Control and Prevention (CDC) have documented infections in bears, foxes, skunks, farmed mink and zoo animals such as tigers and leopards. Earlier this month, avian flu was linked to the deaths of three pet cats in Nebraska.
“This happens when our pets are predating on dead birds,” Hill said. “We knew that this moment would arrive when pets would be affected. If you’re walking a dog, keep it on a leash to keep it away from wildlife, and keep cats indoors.”
Hill said the transmission to mammals may be happening via waterborne transmission, meaning mammals such as whales and seals are getting it from virus in the water, which can lead to mass mortality events. Or transmission is happening when animals such as foxes feed on dead, infected birds like ducks.
The USDA said its Agricultural Research Service began avian influenza vaccination trials in April. They expect data on the efficacy of a single-dose vaccine in May and the results of a two-dose vaccine challenge in June.
Widespread vaccination could be expensive and logistically complicated, said Yuko Sato, a veterinary professor at Iowa State University. As with the coronavirus, it’s a virus that keeps changing, so a vaccine that worked on an earlier version of the virus might not do the job long-term.
“You’d want to give one shot and then a second shot two weeks later, but there are 300 million laying hens,” said Sato, adding that there are also 9.6 billion broilers raised for the meat industry. An effort of that magnitude would have significant costs that would be passed on to consumers’ grocery bills. Also, Sato said, once birds are vaccinated they may not show symptoms of the virus even when infected, as with coronavirus vaccines in humans, so it might make detection much harder. “Vaccines are not a silver bullet, and won’t prevent infection,” she said.
Because of this, some experts worry that widespread vaccination could hurt poultry exports, making it harder for chicken farmers to prove to trading partners that animals are free from disease. (In the last big bird flu outbreak, in 2015, U.S. chicken exports dropped by $1.1 billion, according to USDA data.)
The National Chicken Council, the trade association of meat chickens, does not support the use of a vaccine, said Tom Super, senior vice president of communications for the council. He said most countries, including the United States, won’t import vaccinated poultry due to concerns that vaccines can mask the presence of the disease. “The vaccine will not eliminate the virus,” he said. “Birds can still get [the virus] and may not show signs.”
Carol Cardona, Pomeroy chair in avian health at University of Minnesota, said vaccination would make it more possible to predict and to protect domesticated birds. She warned that not vaccinating could also carry costs and that some animals, such as turkeys, are naturally more vulnerable to the virus. “Not being reactive is half the battle,” she said. “That’s why we have to do vaccination. Why would you not? We have the science. It will take a while, and that means we need to start sooner rather than later.”
Sato said that in the last outbreak, in 2015, much of the spread was from farm to farm, truck tires and dirty boots dragging the virus with them. Heightened biosecurity measures, such as quarantining animals and limiting visitors to facilities, have minimized this, but still, if just a few birds test positive for H5N1, the whole flock is killed and disposed of to minimize spread – which increases costs associated with raising replacement birds, but also for protective gear for workers who must deal with infected animals.
According to Swayne, there have been 874 human cases of avian flu since 1997, about 40 percent fatal. Most of the humans who have contracted avian flu since 1997 have been people who worked with poultry or who have been in “wet” markets where animals are slaughtered.
“Poultry workers are at risk when birds are dying,” Cardona said, but added that she would not rule out a more significant outbreak in humans. “Is it likely in this country? No,” she said. “But never say never with flu.”
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