A Controlled Study to Determine the Immunogenicity and Safety of Cold-adaptive Live Attenuated Influenza Vaccine (Flumist) Administered by the Nasal and Sublingual Route in Healthy Adult Volunteers

Detailed Summary

Background: It is well established that live attenuated organisms can be highly effective vaccines, immune responses elicited can often be of greater magnitude and of longer duration than those produced by non-living antigens and are often able to confer protection after a single dose. Unlike killed influenza vaccine preparations injected by the parenteral route, live influenza vaccines are able to induce potent secretory (mainly IgA) antibody responses in the airway mucosae and can also evoke cell mediated responses. T cell proliferation, cytokine production, cytotoxic T cell responses and antibody-dependent cell cytotoxicity have all been elicited by live attenuated vaccines. There has been a history of the use of live attenuated flu vaccines as safe and effective vaccines for the prevention of flu in animals and humans. Live-attenuated cold-adapted influenza vaccines have been proved to be highly efficacious to protect against clinical fly symptoms. Among these, FluMist, a nasal vaccine formulation developed by Medimmune Inc, has been approved by the US FDA. Recent side by side clinical trials have demonstrated that this nasal vaccine was significantly superior to conventional killed flu vaccine in protecting against flu symptoms. Sublingual administration of live influenza virus at a dose lethal by the nasal route was well tolerated and did not redirect virus to the olfactory bulb. In addition, in a recent Phase I clinical study (NCT00820144) conducted in France, the sublingual administration of recombinant cholera toxin B subunit (rCTB,up to 1 mg) in healthy adult volunteers was found to be safe. A major issue has arisen regarding the ease with which vaccines could be administered to young children, especially infants, and to elderly subjects in whom nasal vaccination has not been possible and/or approved due to difficulties of administering nasal vaccines in infants and to undesired side effects related to frequent rhinitis and sneezing episodes in elderly subjects. This study is designed to investigate the safety, tolerability and immunogenicity of a new route of administration of vaccines, using the nasal FluMist formulation as prototype vaccine. Objectives: To evaluate the immunogenicity and safety of a nasal and sublingual influenza virus vaccine (FluMist) in healthy adult volunteers Study design: This will be a randomized study on a total 40 subjects; each 20 subjects will receive vaccine via nasal and sublingual route, respectively

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