e-Bulletin February 2026
IN THE MEDIA |
A Universal Nasal Vaccine: One Dose, Blocks Transmission
Broad Protection Against Multiple Coronaviruses
A SPH research team led by Professor Leo Poon, Daniel C K Yu Professor in Virology, Chair Professor of Public Health Virology at our School, and Co-Director of The Hong Kong Jockey Club Global Health Institute (HKJCGHI), along with major team members including Dr Nigeer Te, Dr Alex Chin, Dr Gu Haogao and Professor Malik Peiris, has developed a novel live-attenuated coronavirus vaccine candidate, cb1, that can generate broad immunity against multiple beta-coronaviruses with a single intranasal dose. The study shows that cb1 not only prevents severe disease, but also blocks viral transmission in animal models. The study has been published in the Proceedings of the National Academy of Sciences (PNAS) [Link to the publication].
The vaccine demonstrates four key protective features. It offers broad protection with a single dose, providing complete protection in mice against lethal challenges from multiple coronaviruses, including ancestral SARS-CoV-2, Omicron subvariants, and even a common cold coronavirus. Second, it blocks transmission, preventing the spread of SARS-CoV-2 via airborne aerosols and direct contact in hamster models – a feature which is often absent in current intramuscular vaccines. Third, it stimulates robust and durable immunity, generating strong neutralising antibodies and potent T-cell responses in both systemic and mucosal tissues. Finally, as a booster, it overcomes immune imprinting by broadening the antibody responses to cover a wider range of coronaviruses, effectively updating existing immunity.
Professor Leo Poon stated, “Our codon-deoptimisation strategy allows us to substantially weaken the virus without changing a single amino acid. The vaccine replicates only to the extent needed to comprehensively train the immune system, while remaining too weak to cause disease. The breadth of protection we have observed that spans multiple species of beta-coronaviruses is exceptionally promising for the development of a universal coronavirus vaccine”.
