Hong Kong scientists on Thursday unveiled a new needle-free nasal spray influenza vaccine that is capable of providing broad protection against both human and avian flu subtypes, overcoming the limitations of traditional vaccines that require annual updates and target only selected strains.
Announced by the University of Hong Kong’s Li Ka Shing Faculty of Medicine (HKUMed) at a press conference, the scientific team said the innovation aims to pioneer broad-spectrum protection for current and emerging viral threats.
Leo Poon Lit-man, chair professor of Public Health Virology at HKUMed, said at the briefing that influenza is a major respiratory disease that burdens global healthcare systems.
While vaccination remains the most effective preventive measure, he noted that current seasonal vaccines protect against only three selected strains and fail to guard against zoonotic threats like avian influenza.
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He said that an intranasal vaccine induces mucosal immunity in the respiratory tract, offering frontline defense against infections while eliminating needle-related hesitancy, particularly among children.
Led by Poon, the research team used two strategies — genetic modification and codon usage optimization — to develop live-attenuated influenza vaccines capable of effectively triggering immune responses against various influenza virus subtypes.
Poon said the first strategy genetically modifies human influenza viruses to express avian-like surface markers, triggering enhanced immune responses through preexisting antibodies.
Team member Alex Chin Wing-hong, research assistant from the Centre for Immunology and Infection, said the strategy to optimize codon usage involves silent mutations to mimic avian virus traits, ensuring safety while maintaining efficacy.
Chin said the tests in mice demonstrated robust protection against human H1N1, H3N2, and avian H5N1/H7N9 strains, with no pathogenicity observed.
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Chin said the team will start with a nasal spray vaccine targeting the two most significant influenza viruses, with the long-term goal of achieving broad-spectrum protection. He added that this would not only prevent infection from unknown new viruses but also eliminate the need to develop vaccines after a new virus emerges, providing effective prevention with a single vaccination.
Recognized at the 50th International Exhibition of Inventions Geneva 2025 with the Saudi Innovation Excellence Prize and dual gold medals, the technology holds multiple patents and aligns with the World Health Organization’s call for next-generation universal flu vaccines.
Supported by the Hong Kong Jockey Club Global Health Institute, the team will advance Good Laboratory Practice-standard studies to accelerate clinical translation.
