US health officials are gearing up to test a vaccine for poultry to combat the worst bird flu crisis on record — which is raising fears about human spillover.
The Department of Agriculture is involved in developing an updated shot and hopes to start trialing it soon, though it has not offered a timeline. The actual testing process, one it begins, would take at least three months.
While animal vaccines can take years to be licensed parts of the process can be accelerated in emergency cases.
Concerns about the avian flu strain currently circulating have risen in recent weeks after it became evident that it spread from birds to several mammals, including otters and foxes.
The World Health Organization warned this week that the world must prepare for a potential human bird flu pandemic, saying the jump from birds to mammals put us one step closer to human transmission.
Over 58 million birds have died as a result of the avian influenza, either by infection or euthanasia as a means of halting the spread
Entire flocks of poultry have been culled in some instances when a single bird flu case is detected in order to prevent the possible spread of the highly contagious illness
Erin Spackman, a virologist who studies avian influenza vaccines at the USDA told CBS: ‘There are a lot of moving parts to this kind of testing. And some of it is just pure logistics of getting everything in place to do the testing, getting the vaccines that are updated, getting things from parties that are involved, different manufacturers.’
While it is not always a requirement for animal shots to be licensed by the USDA, the trials will offer an early independent evaluation of how well a vaccine works in this case.
USDA spokesperson Mike Stepien told CBS News: ‘The decision to proceed with vaccination is complex, and many factors must be considered before implementing a vaccination strategy.’
The USDA did not disclose details about the shots it would use in testing, though there are a few in development.
And at the Pirbright Institute in the UK, scientists are developing an improved shot that involves tagging flu virus proteins with a marker that makes them easier for antigen-presenting cells (APCs) to capture. This generates faster and stronger immune responses to the bird flu strain compared to the inactivated virus vaccine that is the current standard.
Scientists at the University of Wisconsin’s School of Veterinary Medicine for example are working on an avian flu vaccine that uses tiny particles even smaller than the width of a human hair to deliver immunity by sending pathogen-like signals to cells.
If an updated shot proves effective, that would open the door to USDA approval followed by a thorough vaccination campaign that seeks to reach the affected commercial poultry industry.
While shots for the purpose of fending off avian flu have been used in the past, the USDA has not approved one for what is considered ‘highly pathogenic’ avian influenza.
The avian flu of the ‘low pathogenicity’ category is not uncommon in wild birds and typically causes few or no signs of infection.
But a ‘highly pathogenic’ strain is highly contagious and deadly to domestic poultry.
The USDA says in the event that the latter sweeps domestic poultry farms, farmers must quickly eradicate the disease by culling the flocks.
Avian flu has stricken wild birds in every state with farmers in 47 states having detected it in domesticated birds used for food.
Another complicating factor is a geopolitical one. Countries have been hesitant to vaccine birds in the past for fear that it would imperil the US’ ability to export poultry.
Dr. David Swayne, a Georgia-based veterinarian told CBS News: ‘What is the trigger point of when you might use vaccination?
‘And that’s what they’re looking at. Is it so many birds in a poultry farms in an area getting infected? Or is it a certain amount of economic loss?
‘Or is it because a neighboring state has the virus in poultry, and you’re concerned? So there’s those are really the tough, tough questions.’
While countries where the avian flu is endemic, including Egypt and Indonesia, have effective vaccines for their poultry, they don’t export much of it.
But using shots in the US, which sends nearly a fifth of its poultry abroad, could complicate exportation thanks to the DIVA differentiating infected from vaccinated animals problem, which describes the strategy of trying to determine whether avian flu antibodies in poultry indicates whether a bird is actually infected with avian influenza, or just has avian influenza antibodies after vaccination.
Egg prices have soared in the US as a result of the avian flu in conjunction with inflation, supply-chain issues, and worker shortages
Top virologists from across the world have sounded the alarm after tests confirmed the H5N1 strain was spreading between mammals such as mink (pictured). The outbreak occurred in a farm in Galicia, north west Spain, in October which housed 52,000 of the animals
Scientists developing avian flu vaccines aim to design one that marks the antibodies they create in birds, demonstrating to regulatory agencies that they originate from the vaccine, not disease. This would provide reassurance to different governments, allowing the international poultry trade to continue without fear of inadvertently importing avian flu.
Several European countries are further along in developing a vaccine that satisfies the DIVA strategy that would work with poultry exports.
The bird flu crisis in the US is the worst it has been since the 2014-2015 outbreak which saw 50 million birds dead.
Since the first US case of the latest outbreak was reported in January 2022, 58 million birds, mostly commercially-raised poultry, have died as a result of either bird flu infection or being put down to quell transmission.
Avian flu poses little threat to humans, according to the Centers for Disease Control and Prevention. The agency has said: ‘No known human-to-human spread has occurred with the A(H5N1) virus that is currently circulating in birds in the United States and globally.
‘During past H5N1 bird flu virus outbreaks that have occurred in poultry globally, human infections were rare. Globally since 2003, countries have reported rare, sporadic human infections with H5N1 bird flu viruses to the World Health Organization (WHO).’
It has made its way to other mammals, though, including sea lions, foxes, opossums, and bears, prompting the WHO to raise a red flag.
WHO Director General Tedros Adhanom Ghebreyesus said Wednesday: ‘For the moment, the WHO assesses the risk to humans as low… But we cannot assume that will remain the case and we must prepare for any change in the status quo.’
Infection in humans is rare but when it does strike humans, it kills in about 56 percent of cases.