Study of Immune Responses After Vaccination Against Seasonal Influenza Virus and Against Influenza H1N1-v Pandemic Virus in a Medical Staff. (FLU-HOP)

Study of Immune Responses After Vaccination Against Seasonal Influenza Virus and Against Influenza H1N1-v Pandemic Virus in a Medical Staff.

Study of Immune Responses After Vaccination Against Seasonal Influenza Virus and Against Influenza H1N1-v Pandemic Virus in a Clinical Staff (FLU-HOP)

This project may help to answer several fundamental questions related to public health regarding vaccination against influenza viruses and regarding the influenza A(H1N1)v pandemy: What is the immunologic efficacy in terms of antibodies response of the vaccination against the seasonal (2009-2010) influenza virus and against the A(H1N1)v virus in the clinical staff? Moreover, it may help to answer questions related to the use of a vaccine against influenza virus variants emerging in the French population: Before the vaccination: What is the status of the residual anti-H1N1 seasonal viruses immunity and of the anti-A(H1N1)v immunity in the population stratified by age and taking into account the multiplicity of the prior seasonal vaccinations? What is the level of the cellular and humoral cross-reactivity between the different H1N1 strains? After the vaccination: What is the intensity of the anti-vaccine immune response as a function of the age of the population ad of the prior seasonal vaccinations? What is the level of the cellular and humoral cross-reactivity after vaccination as a function of the age of the population and of the multiplicity of the prior seasonal vaccinations?

Evaluation of the intensity of the humoral and cellular immune responses of the anti-A(H1N1)v vaccine in a medical care population as a function of the age and of the prior seasonal anti-influenza vaccinations.

Investigate the quality of the humoral and cellular immune responses induced by the seasonal anti-influenza vaccine as a function of the age and of the prior seasonal vaccinations.

Determine the cross-reactivity of the humoral and cellular immune responses as a function of the age and of the prior seasonal vaccinations

Assess the occurence of flu episodes and their severity during the 2009-2010 season as a function of the age of the population. Then, the correlation between the flu episodes and and the immunologic results is to be evaluated.

Evaluate the perception of the anti-influenza vaccination in a medical care population in the current H1N1v pandemy context.

Inclusion Criteria: Healthy volunteers Age superior or equal to 20 years Women with childbearing potential using contraception Exclusion Criteria: Documented immune depression Current immunosuppressive therapy Pregnancy (documented by a positive pregnancy test) Breast feeding women Documented allergy or hypersensitivity to vaccines Documented acute or chronic inflammatory disease Concomitant participation to another clinical trial