Organ transplant patients and staff members at the Transplant Institute have received pandemic H1N1 influenza vaccine (Pandemrix) and specific antibody production was measured by haemagglutination inhibition according to the clinical guidelines and policy, respectively. This study retrospectively assessed the immune response after vaccination.

A total of 100 organ transplant patients and 36 healthy controls were included in the study. All individuals were vaccinated between October and November 2009 and received 2 doses of Pandemrix. Serum samples were collected at baseline before vaccination and 1 month after the first and second vaccination. Individual hemagglutination-inhibiting serum antibody titers were measured.Frequency of > 4 -fold increase in antibody titers and seroconversion from non-protective prevaccination titers to protective postvaccination titers were recorded. Adverse events were reported.

Inclusion Criteria:

Cohort number 1:Organ transplant patients who were vaccinated and serum sample drawn at baseline.

Cohort number 2: Staff members who were vaccinated and serum sample drawn at baseline.

Exclusion Criteria:

Cohort number 1: Organ transplant patients who were vaccinated and no serum sample drawn at baseline.

Cohort number 2: Staff members who were vaccinated and no serum sample drawn at baseline.

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