Observational Study to Assess Safety of H1N1 Pandemic Influenza Vaccine

Inclusion Criteria: Male and female subjects, per indication on license or per official vaccine recommendations, will be eligible for participation in this study if: * They will be administered CELVAPAN (= Baxter´s H1N1 pandemic influenza vaccine) * They are 2 months of age or older at the time of first vaccine administration * Their medical history is available * The investigator believes they will comply with the foreseen vaccination schedule and will reliably observe signs or symptoms of adverse events during the observational period * They and/or their parent(s)/legal guardian(s) provide written informed consent, and assent where appropriate, prior to study entry according to national law Exclusion Criteria: Male and female subjects will be excluded from participation in this study if: * They have already been administered another H1N1 pandemic vaccine * They have any contraindication to vaccination (as per the Summary of Product Characteristics and/or relevant national immunization guidelines)