(Xinhua)
Updated: 2008-01-29 20:22

SEOUL -- South Korean researchers on Tuesday said they have discovered a new needle-free vaccination approach that may be safer to use and elicit a broader range of immune responses than conventional methods.

The Seoul-based International Vaccine Institute (IVI) said the novel approach calls for the administration of vaccines under the tongue, triggering immune responses in various mucosal tissues in the respiratory, digestive and reproductive tracts, which are major entry portals of pathogens into the body.

At present, most vaccines are given by needle shots into the bloodstream, with others being ingested or inhaled. Using needles, however, runs the risk of causing secondary infections in countries where medical conditions are poor.

Song Joo-hye and Kweon Mi-na, who led the research effort, said the "sublingual" administration of a flu vaccine on mice showed the animals developing a robust immune response in their lungs, and they were fully protected when they were later exposed to a severe form of influenza virus.

"Test results suggest that this method of vaccine administration poses no risk of antigen redirection to the central nervous system, which is a potential risk of giving influenza drugs intranasally," said Kweon.

The IVI, established in 1997 as a United Nations Development Program initiative devoted to the development of new vaccines to help the world's poorest people, said the findings were published in the latest issue of the US-based Proceedings of the National Academy of Sciences (PNAS).

Cecil Czerkinsky, IVI deputy director for laboratory science, said that besides the convenience of giving vaccinations in this way, the new approach showed the potential for disseminating immunity to a broader range of organs compared to classical routes.

"If these findings can be replicated in humans, they could pave the way for the development of a new generation of vaccines that could be used for mass vaccinations against respiratory infections, including the pandemic avian-human influenza viruses," the expert said.

The latest study, meanwhile, is a further development of joint research conducted with France's National Institute for Health and Medical Research and Gothenburg University of Sweden.

The studies found that the sublingual approach overcomes drawbacks linked to oral administration of vaccines like degradation of antigens during their transit through the gastrointestinal tract, and failure to introduce strong immune responses in the respiratory tract.