Immunogenicity (Humoral and Cellular Immune Responses) and Safety of the Seasonal Flu Vaccine in Elderly and in SOT Recipients

This study will assess the effect of a different dose of the seasonal flu vaccine 2013-2015 on the immune response to improve the investigators understanding of cellular and humoral immune responses induced. The scope of this study is to determine the profile of cellular activation and antibody production in the ageing immune system following flu immunization. This study will enroll 100 male or female subjects ≥65 year old and 90 transplant recipients. These persons will be deemed to be " at risk " in case of influenza infection and should be vaccinated according to Swiss Federal Office of Public Health. A medical doctor from the CHUV will inform the patients about the present study and ask them whether they would be willing to participate in the study. All subjects will be distributed between the two groups according to a computer-generated randomization sequence. The randomization will be done in blocks to ensure balance across groups. The participants and site staff will not be blinded due to the different administration assignments. Group 1 subjects will receive a single dose and group 2 subjects a double dose of MUTAGRIP® manufactured by Sanofi Pasteur containing A/California/7/2009 (H1N1); A/Texas/50/2012 (H3N2); B/Massachusetts/2/2012. Vaccine immunogenicity and safety will be assessed 1, 2, 4 and 24 weeks after vaccination. Study duration per volunteer is 6 months after vaccination.