Clinical assessment of a novel simian adenovirus-vectored influenza vaccine designed to induce broadly protective immunity

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The influenza vaccines that are used at present have a number of disadvantages. The vaccines have to be reformulated every year to keep up with changes in the viruses that are circulating, and people have to be revaccinated every year. About one year in 20, the virus that is circulating changes after the vaccine formulation for that year has been decided, and then the vaccine does not work well. At best the trivalent inactivated vaccine (TIV) has an efficacy of 60 % in adults aged under 65 years, and lower than that in older people who are the main group targeted for vaccination. At the Jenner Institute we have tested a new type of influenza vaccine using a live virus vaccine, similar to the smallpox vaccine, which has been attenuated to prevent it from causing disease and make it very safe to use. Our first clinical trials with this new vaccine MVA-NP+M1 showed that it was very effective at boosting T cell immune responses to influenza, and that in a small study, fewer vaccinated than non-vaccinated volunteers who were then exposed to influenza virus developed symptoms of influenza infection. Importantly, the vaccine was very immunogenic in older volunteers, which is not the case with TIV.We now wish to conduct clinical trials with a different viral vectored influenza vaccine, this one based on an attenuated adenovirus, since in clinical trials of vaccines against other diseases this type of vaccine was even more immunogenic and the immune responses lasted for longer after vaccination.The first ever clinical trials of this new vaccine, ChAdOx1 NP+M1, have already started, in a small study designed to work out the best dose to use. We are now applying for funding to do two trials with this new vaccine. The first will be in healthy volunteers aged 18 to 50 years. Half of them will receive ChAdOx1 NP+M1, and half will receive MVA-NP+M1, so that we can compare the immunogenicity of the two vaccines. Later, they will all receive a second vaccination with the vaccine that they did not receive the first time, so that we can see the effect of giving first one vaccine and then the other, as this is expected to produce the strongest and most durable response.The second trial will be in volunteers aged over 50 years who will receive a single dose of ChAdOx1 NP+M1 to determine immunogenicity in older people. After these studies have been completed, we will be able to design much larger studies to find out how effective the vaccine is at preventing people from becoming ill with influenza