Researchers at WashU Medicine have developed a nasal vaccine against the highly pathogenic H5N1 bird flu virus, commonly known as bird flu.
When the vaccine was tested on rodents, it produced a strong immune response and prevented infections in animals exposed to H5N1.
Since H5N1 avian flu was first discovered in the US in 2014, it has been transmitted from wild birds to farm animals and then to humans. Since 2022, there have been more than 70 human cases in the U.S., including two fatalities.
The virus continues to circulate among animals, giving it the opportunity to spread among humans and potentially cause another pandemic.
To reduce the possibility of such an event, researchers at Washington University School of Medicine in St. Louis published their results in Cell reports medicineof an intranasal vaccine that, when tested on hamsters and mice, induced strong immune responses and even prevented infections in exposed animals.
“This particular version of bird flu has been around for a while, but the unique and completely unexpected event of species switching to dairy cows in the United States was a clear sign that we need to prepare for the eventuality that a pandemic could emerge,” said Jacco Boon, PhD, professor in the WashU Medicine John T. Milliken Department of Medicine and co-senior author of the study.
“Our nasal and upper respiratory tract vaccine – and not the vaccine people are used to – can protect against upper respiratory tract infections and against severe disease. This could provide better protection against transmission, because it protects against infections in the first place,” the expert added.
The researchers tested the nasal vaccine in hamsters and mice and found almost complete protection against infections.
In comparison, current seasonal flu vaccines provided little protection against H5N1 infection.
Both animal models showed better protection against H5N1 infection by the nasal spray vaccine than by the same formula given via traditional intramuscular immunization.
“We showed that this nasal vaccine delivery platform that we conceived, designed and implemented at WashU Medicine can prevent an H5N1 infection from taking hold in the nose and lungs,” said Diamond, co-senior author of the study. “Delivering the vaccine directly to the upper respiratory tract, where you most need protection against respiratory infections, can disrupt the cycle of infection and transmission. That is critical to slowing the spread of infections for H5N1 and other influenza strains and respiratory infections.”
The researchers have now determined that their next steps include conducting additional studies of the vaccine in animals and organoids representing human immune tissue, and developing new versions of the vaccine that further minimize the effects of previous seasonal flu infections and promote greater antiviral responses.
