SEOUL, Korea - The International Vaccine Institute (IVI) has found a way to administer vaccines sublingually without needles. In two recent studies, IVI scientists and their collaborators have established that vaccines administered under the tongue can elicit a broad range of immune responses in various mucosal tissues, including the respiratory, digestive, and reproductive tracts, which are major entry portals of microbial pathogens into the body. The IVI, based in Seoul, is the world´s only international organization devoted exclusively to developing new vaccines for the poor.

Researcher Song Joo-Hye and her colleagues at the IVI have found that sublingual administration of an experimental flu vaccine is highly effective in protecting mice from influenza virus infection. When the flu vaccine was applied under the tongue, animals developed robust immune responses in their lungs and were fully protected from the disease when later exposed to a severe form of influenza virus.

Dr. Kweon Mi-na, chief of the IVI´s mucosal immunology laboratory who oversaw the study, said, "Moreover, the study suggested that this method of vaccine administration poses no risk of antigen redirection to the central nervous system, which is a potential risk of administering influenza vaccines intranasally." The study is published as a distinguished article in the current issue of the Proceedings of the National Academy of Sciences in the United States (Online early edition was issued on January 28).

This study builds on the IVI´s earlier study, conducted in collaboration with Inserm (National Institute for Health and Medical Research) in France and Gothenburg University in Sweden. In addition to offering a convenient and safe way to deliver vaccines without needles, scientists in that study found the sublingual route helps overcome the 2 main drawbacks of orally administered vaccines: degradation of antigens during their transit through the gastrointestinal tract, and failure to induce strong immune responses in the respiratory tract. This study appeared in the December issue of Vaccine.

"These studies provide a basis for further human testing of this alternative form of needle-free vaccination. Aside from its convenience, sublingual vaccination appears to disseminate immunity to a broader range of organs than the classical routes of injecting or ingesting vaccines," said Dr. Cecil Czerkinsky, IVI Deputy Director-General for Laboratory Science. "If these findings are replicated in humans, they could pave the way for the development of a new generation of vaccines that could be used for mass vaccination against respiratory infections, including the pandemic avian-human influenza viruses."

Dr. John Clemens, IVI Director-General who is a world authority on vaccine evaluation, said, "These studies are important milestones for the IVI. Sublingual vaccination is an entirely new approach to the delivery of vaccines; this approach offers the possibility of vaccinating against a variety of infections without the risks posed by delivering vaccines with needles."

The International Vaccine Institute (IVI) is the world’s only international organization devoted exclusively to developing and introducing new and improved vaccines to protect the world’s poorest people, especially children in developing countries. Established as an initiative of the United Nations Development Program in 1997, the IVI operates under a treaty signed by 40 countries and the World Health Organization. The Institute conducts research in more than 20 countries of Asia, Africa and Latin America on vaccines against diarrheal infections, bacterial meningitis and pneumonia, as well as Japanese encephalitis and dengue fever, and develops new and improved vaccines at its headquarters in Seoul. For more information, please visit www.ivi.int

Attachement : Absorption of antigen onto the murine sublingual mucosa