Increased immunogenicity of the MF59-adjuvanted influenza vaccine compared to a conventional subunit vaccine in elderly subjects

Three-hundred and eight outpatient elderly subjects (greater than or equal to 65 years) were randomly assigned to receive the MF59-adjuvanted influenza vaccine (FLUAD; n = 204) or a conventional subunit influenza vaccine (AGRIPPAL S1; n = 104) in order to compare the safety and immunogenicity of the two vaccines. Although mild pain at the injection site was reported more frequently by subjects immunised with the adjuvanted vaccine, both vaccines were shown to be safe and well tolerated. The adjuvanted vaccine was more immunogenic as indicated by higher post-immunisation geometric mean titres (GMTs) and by higher proportions of subjects with post-immunisation greater than or equal to four fold increases of antibody titres or subjects with greater than or equal to 1/160 post-immunisation HI titres. These differences, statistically significant for all three strains after immunisation, indicated that, by addition of the MF59 adjuvant emulsion, conventional subunit influenza antigens acquire an enhanced immunogenicity without any clinically significant increase of their reactogenicity.