Placebo Controlled Study to Generate Data Characterising Clinical Events, Physiological Responses and Immune Responses

Inclusion Criteria: * Healthy male or female subjects aged 18-45 years inclusive. * Male: Female ratio - Screening will ensure that no more than 2/3 of the population should be of either male or female * The subject is, in the opinion of the investigator: healthy based on medical history and clinical exam, with no active disease process that could interfere with the study endpoints. * Has a body Mass Index ≥18 and ≤30 * Is able to read and understand the Informed Consent Form (ICF), and understand study procedures. * The subject has signed the ICF. * The subject is available for follow-up for the duration of the study. * The subject agrees to abstain from donating blood during their participation in the study, or longer if necessary. * If the subject is a heterosexually active female, she is willing to use an effective method of contraception with partner (oral contraceptive pill; intrauterine device; injectable or implanted contraceptive; condoms incorporating spermicide if using these; physiological or anatomical sterility) from 30 days prior to, and 3 months after, vaccination. Willing to undergo urine pregnancy tests prior to vaccination at screening. * The subject has venous access sufficient to allow blood sampling as per the protocol. Exclusion Criteria: * Pregnant or lactating at any point during the study from screening to final follow up. * Hypersensitivity to the active components of FLUAD, any of the excipients, eggs, chicken proteins, kanamycin and neomycin sulphate, formaldehyde, and cetyltrimetholammonium bromide or those who have had a previous life-threatening reaction to previous influenza vaccinations. * Presence of primary or acquired immunodeficiency states with a total lymphocyte count less than 1,200 per mm3 or presenting other evidence of lack of cellular immune competence e.g. leukaemias, lymphomas, blood dyscrasias, or patients receiving immunosuppressive therapy (including regular use of oral or parenteral corticosteroids). * Use of any immune suppressing or immunomodulating drugs within 6 months of Visit 1. * Regular use of non-steroidal anti-inflammatory drugs (oral or parenteral route) within 6 months of Visit 1 considered by the study physician as likely to interfere with immune responses. * Current intake of excessive amounts of alcohol and/or caffeine (as evaluated by the investigator) and not willing to adapt this use during the study period. * Currently performing extreme physical activities (as evaluated by the investigator) and not willing to adapt this use during the study period. * Receipt of a vaccine within 30 days of visit 1, or requirement to receive another vaccine within the study period. * Vaccination with the 2014/2015 seasonal influenza vaccine and/or any other seasonal influenza vaccine within the last 6 months before the first study visit. * Presence of an acute severe febrile illness at time of immunisation. * History of alcohol, narcotic, benzodiazepine, rilatine, or other substance abuse or dependence within the 12 months preceding Visit 1. * Currently participating in another clinical study with an investigational or non-investigational drug or device, or has participated in a clinical trial within the 3 months preceding Visit 1. * Any condition that, in the investigator's opinion, compromises the subject's ability to meet protocol requirements or to complete the study. * Receipt of blood products or immunoglobin, or blood donation, within 3 months of screening. * Unable to read and speak Dutch or English to a fluency level adequate for the full comprehension of procedures required in participation and consent.