Bird flu has been around for a long time. Originally infecting only birds, highly pathogenic avian influenza (H5N1) was first found in dairy cattle in March 2024.
Because influenza had never been known to jump to a different species, this caught the attention of Eric Weaver, director of the Nebraska Center for Virology and University of Nebraska-Lincoln professor.
“Dairy cattle aren’t known to have influenza, and so it struck me that something was very much out of place to see the dairy cattle with bird flu,” he said.
Weaver set out on a mission to produce a broad-spectrum vaccine that would hold up over time with different strains. A research team tested 28 years of H5N1 evolution to create a new HPAI vaccine with important implications for the livestock industry once it hits the market within the next few years.
By going back to the ancestral strain, the team incorporated all strains in the population.
“That’s where the strength of the vaccine comes in,” Weaver explained. “We saw good protective immune responses against all 28 years of viral evolution. So, the idea would be that this vaccine would then protect against specific variants, as well as variants outside of that.”
Although bird flu has a low mortality rate in dairy cattle, production slows and causes a large economic impact to already tight margins in the dairy industry. Weaver’s team wanted to solve this problem and potentially protect other species in the process.
Preventing bigger problems
By reducing the infection and circulation of influenza in dairy cattle, the vaccine can help reduce mutations of H5N1 that could spread between animals or even to humans. This research prompts the question: Can this vaccine protect the farm and the farmer?
“The longer we have the bird flu circulating, it will eventually mutate into a form that has a higher fitness and a higher replication. It’s just what viruses do,” Weaver said. “Anything that would transmit animal to animal, mammal to mammal, like what we’re seeing in dairy cattle, might transmit human to human. Transmission of bird flu would be extremely consequential.”
Weaver added that the earlier virologists get ahead of viruses such as H5N1, the better for all livestock and humans.
This vaccine originally started as a human vaccine against bird flu. However, by modifying it, Weaver and his team have successfully tested the vaccine in mice, ferrets, pigs and dairy cattle. Under lethal challenge studies in mice, the vaccine proved 100% successful.
This gave hope to the UNL team that future protections with other species will be effective.
Making it work for the farm
Aside from bird flu being a crucial virus to control, producers need a return on investment. Because dairy cattle can still survive HPAI, the vaccine would need to justify the costs involved in the weeks of milk production loss. Weaver assures producers that when this vaccine hits the market, it will be affordable.
“The way the vaccines are made and the doses that we’re using, it’s already in that affordable range,” he said. “If we scaled up and we took this to market, it would absolutely be affordable in the industry.”
Because the cost of the vaccine is already affordable, researchers want to focus on ease of use for producers. In original studies, they tested intranasal delivery simultaneously with the intramuscular vaccine. By breaking out these two delivery methods, they will determine whether the effectiveness stays the same.
“If it turns out that the intranasal gives us long-term protection and good protection, then that’ll probably be an easier vaccine to deliver, because then you don’t have your farmhands working with needles,” Weaver said.
The biggest goal of the research team is to create an all-in-one vaccine that will protect all livestock species.
Weaver reflected on the implications of beef cattle being infected with bird flu.
“While the economic impact of H5N1 outbreaks in dairy cattle can be measured through production losses and herd management costs, the broader socioeconomic risks of continued H5N1 virus circulation in the dairy herds are far more difficult to quantify,” Weaver said.
“There is a concern that this virus could evolve increased transmission efficiency in cattle populations, especially in beef cattle, or more significantly, to acquire sustained human-to-human transmission. These outcomes could have profound consequences for public health, agriculture and the economy.”
By being proactive and making this vaccine available while keeping it affordable, Weaver’s team is on the brink of protecting the farm and the farmer from bird flu.