• To evaluate the humoral immune response induced by the study vaccines in term of anti-haemagglutinin antibody titers.
• To evaluate the safety and reactogenicity of the study vaccines in term of solicited local and general adverse events, unsolicited adverse events and serious adverse events"

• To evaluate the humoral immune response induced by the study vaccines in term of serum neutralizing antibody titers
• To evaluate the cell-mediated immune response induced by the study vaccines in term of frequency of influenza-specific CD4/CD8 T lymphocytes

Today, the leading contender for the next pandemic of influenza is H5N1, a strain of avian virus. Prevention and control of a pandemic will depend on the rapid production and worldwide distribution of specific pandemic vaccines. Candidate 'pandemic-like' vaccines must be developed and tested in clinical trials to determine the most optimal formulation and the best vaccination schedule.This study is designed to test in healthy adults aged between 18-60 years the reactogenicity and immunogenicity of one and two administrations of a candidate pandemic H5N1 vaccine formulated from Split Virus. The vaccines contain different antigen doses . For each dose, adjuvanted vaccine will be compared to the plain vaccine in order to detect the optimal formulation for immunization against the H5N1 influenza strain.

• Biological: 4 adjuvanted pandemic influenza candidate vaccines
• Biological: 4 non-adjuvanted pandemic influenza candidate vaccines

• Leroux-Roels I, Bernhard R, Gérard P, Dramé M, Hanon E, Leroux-Roels G. Broad Clade 2 cross-reactive immunity induced by an adjuvanted clade 1 rH5N1 pandemic influenza vaccine. PLoS ONE. 2008 Feb 27;3(2):e1665.
• Leroux-Roels I, Borkowski A, Vanwolleghem T, Drame M, Clement F, Hons E, Devaster JM, Leroux-Roels G. Antigen sparing and cross-reactive immunity with an adjuvanted rH5N1 prototype pandemic influenza vaccine: a randomised controlled trial. Lancet. 2007 Aug 18;370(9587):580-9.

Inclusion criteria:

• A male or female between, and including, 18 and 60 years of age at the time of the first vaccination.
• Healthy subjects as established by medical history and clinical examination before entering into the study.
• If the subject is female, she must be of non-childbearing potential.

Exclusion criteria:

• Administration of any vaccine during the period starting 15 days before the first administration of the study vaccine and ending 21 after the second one.
• Administration of an influenza vaccine other than the study vaccines during the entire study period.
• Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the first administration of the study vaccine.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination
• History of hypersensitivity to vaccines.
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine.
• Acute clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests.
• Acute disease at the time of enrolment.
• Administration of immunoglobulins and/or any blood products within the three months preceding the first administration of the study vaccine or during the study.
• lactating women
• Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days prior to the first vaccination, or planned use during the study period.