Vaccination without tears
A new technology allows vaccines against respiratory diseases to be delivered directly to the site of initial infection - the nose. Painless, and easier to administer than an injection, it also produces an enhanced immune response. Background As the recent flu `epidemic' across Europe showed, viral and bacterial respiratory infections still pose a major threat to the health of the young and elderly, in Europe as well as in the developing world. The effectiveness of large-scale immunisation programmes relies on their reaching a significant proportion of the population. While fear of the needle is a significant disincentive to inoculation, in many countries the syringes themselves now pose a real hazard in the spread of AIDS. Nasal vaccines have been under development for some time, and will shortly appear on the market. They should reduce the burden on healthcare resources and encourage take-up of immunisation. The question is whether vaccines delivered via this route are absorbed as well as intramuscular vaccines. Description, impact and results In theory, nasal vaccination against respiratory diseases such as flu, whooping cough and diphtheria should provide improved protection. Intramuscular injection of a vaccine elicits a strong systemic immune response, characterised by the production of IgG antibodies which attack the target antigen in the bloodstream. But respiratory diseases enter the body through the mucosal lining of the nose or lungs. Delivering the vaccine in the nose itself stimulates the production of local secretory antibodies, providing an additional first line of defence. Chitosan greatly enhances this effect by opening up the junctions between the cells of the mucosal lining, allowing more of the protein molecules in the vaccine to reach the lymphoid tissue where antibodies are produced. The diphtheria vaccine is still some years from full clinical application, but chitosan-mediated nasal flu inoculation may be available as early as 2002. Working partnerships The Innovation project "Mucosal vaccines for respiratory diseases based upon nasal administration" addresses the problem of improving the nasal delivery technique by using a patented technology already successfully applied to the delivery of other medicines. British company Danbiosyst has shown that absorption of certain drugs across the nasal mucosa is greatly enhanced by chitosan. This non-toxic substance, derived from shellfish, is already widely used in dietary aids. Now the technology is being optimised for a new, genetically detoxified diphtheria vaccine developed by Italian pharmaceutical company Chiron Biocine. Irish researchers at the University of Maynooth are studying the mechanism by which chitosan aids nasal vaccine delivery, and the impact on immunity. Progress is extremely promising, and Phase 1 clinical trials with human volunteers will be launched before the end of the three-year project in 2000. Project title: Mucosal vaccines for respiratory diseases based upon nasal administration Fourth Framework Programme Innovation Programme Project reference: IN10100l