Researchers at WashU Medicine have developed a nasal vaccine against the highly pathogenic H5N1 avian influenza virus which is commonly known as bird flu.
When the vaccine was tested in rodents, it induced a strong immune response and prevented infections in animals exposed to H5N1.
Since it was first detected in the U.S. back in 2014, H5N1 avian influenza, transmitted from wild birds to farm animals and then to people, causing more than 70 human cases in the U.S. since 2022, including two fatalities.
The virus still continues to circulate among animals, giving it the opportunity to develop the ability 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 Medicine, of an intranasal vaccine that produced strong immune responses when tested in hamsters and mice and even prevented infections in exposed animals.
“This particular version of bird flu has been around for some time, but the unique and totally unexpected event where it jumped across species into dairy cows in the United States was a clear sign that we should prepare for the event that a pandemic may occur,” said Jacco Boon, PhD, Professor, WashU Medicine John T. Milliken Department of Medicine and co-senior author of the study.
“Our vaccine to the nose and upper airway - not the shot-in-the-arm vaccine people are used to - can protect against upper respiratory infection as well as severe disease. This could provide better protection against transmission because it protects against infection in the first place,” the expert added.
The researchers tested the nasal vaccine in hamsters and mice and observed near-complete protection against infection.
In comparison current seasonal influenza vaccines provided little protection against H5N1 infection.
Both animal models showed better protection against H5N1 infection from the nasal spray vaccine than from the same formula being given through traditional intramuscular immunization.
“We’ve shown that this nasal vaccine delivery platform we conceived, designed and conducted initial testing on at WashU Medicine can prevent H5N1 infection from taking hold in the nose and lungs,” said Diamond, the co-senior author of the study. “Delivering vaccine directly to the upper airway where you most need protection from respiratory infection could disrupt the cycle of infection and transmission. That’s crucial to slowing the spread of infection for H5N1 as well as other flu strains and respiratory infections.”
The researchers have now determined that their next steps are to conduct additional studies of the vaccine in animals and in organoids representing human immune tissue, as well as to develop new versions of the vaccine that further minimize the effects of prior seasonal influenza infection and that promote greater antiviral responses.