Nasal spray vaccine protects against bird flu in mice

WashU Medicine researchers led by Jacco Boon, a professor in the John T. Milliken Department of Medicine, report that an experimental bird flu vaccine provides strong immune protection in mice, including in animals previously vaccinated against seasonal flu. Because pre-existing immunity from prior seasonal influenza infection or vaccination could diminish the efficacy of H5N1 vaccines, showing that the new vaccine succeeds alongside existing immunity is a crucial milestone.

Louis edited by Lisa Lock, reviewed by Robert Egan Lisa Lock Scientific Editor Meet our editorial team Behind our editorial process Robert Egan Senior Editor Meet our editorial team Behind our editorial process Editors' notes This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: fact-checked peer-reviewed publication trusted source proofread The GIST Add as preferred source Intranasal immunization with H5 HA nanoparticle vaccine (H5-MNP) protects against lethal clade 2.3.4.4b virus challenge. DOI: 10.1038/s41541-026-01523-8 WashU Medicine researchers led by Jacco Boon, a professor in the John T.

Building on Boon's prior work on bird flu vaccines delivered nasally, the new study, published July 10 in npj Vaccines, shows that delivering the vaccine to the nose offers better protection against infection in the nose and upper airways than a traditional injection. The novel vaccine pairs a key protein on the surface of the H5N1 bird flu virus with an immune-boosting ingredient used in some newer COVID-19 and malaria vaccines to prime the immune system to attack this protein. In mice already vaccinated against seasonal flu, a single dose of the H5N1 vaccine generated strong virus-fighting antibodies against the strain of bird flu identified in the 2024 U.S.

Outbreak, which heavily affected the poultry and dairy industries and caused two human deaths. In contrast, mice with no prior flu exposure required two doses of the new vaccine to achieve the same level of protection. Unlike many existing vaccines, this vaccine does not rely on eggs for production, making it more practical to manufacture large quantities during an outbreak.

Future testing will determine whether it also blocks disease transmission. Publication details Kelly Pyles et al, Intranasal and intramuscular H5-Matrix-M nanoparticle vaccines protects against highly pathogenic H5N1 influenza virus in mice, npj Vaccines (2026).

DOI: 10.1038/s41541-026-01523-8 Journal information: npj Vaccines Clinical categories Infectious diseases Common illnesses & Prevention Clinical pharmacology Louis Who's behind this story? Lisa Lock BA art history, MA material culture.

Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021.

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