Organ transplant patients who participated in a retrospective study and received 2009 Pandemrix vaccine during autumn 2009 are included in this study.

The main aim is to determine the H1N1 antibody levels one year after Pandemrix in comparison to healthy controls. The secondary aim is to examine the booster effect of 2010 Fluarix in patients and controls.Side effects to Fluarix vaccine are registered.

Organ transplant patients and staff members of the Transplant Institute who were vaccinated 2009 and received 2 doses of 2009 H1N1 influenza vaccine (Pandemrix) will be asked to participate in the study.

Serum samples will be collected approximately one year after completed vaccination with Pandemrix and analysed for haemagglutination -inhibiting antibodies against H1N1.The frequency of individuals with remaining protective titers will be examined.

The same individuals will be vaccinated with Fluarix containing antigen from Influenza A California/7/2009(H1N1, A/Perth/16/2009 (H3N2) and B/Brisbane/60/2008. The booster effect will be measured one month later.

Inclusion Criteria Cohort number 1: Organ transplant patients who were vaccinated with Pandemrix 2009 and written informed consent received

Cohort number 2: Staff members who were vaccinated with Pandemrix 2009 and written informed consent received

Exclusion Criteria:

Patients or controls who are allergic to formaldehyde, gentamycin sulphate or natrium deoxycholate or have other contraindications against to Fluarix vaccination.

Transplant patients at the out-patient clinical ward and staff members of the Transplant Institute, Sahlgrenska University Hospital