The focus of this study is to assess the safety of GSK's H1N1 vaccine in real life conditions as soon as the vaccine is used, in a mass vaccination programme, and with a system for rapid generation, communication and evaluation of safety data.

This study is a commitment to the European Medicines Agency (EMEA), as part of GlaxoSmithKline Biologicals' (GSK Biologicals') risk management plan for pandemic influenza vaccination.

Collaborator: Medicines and Healthcare products Regulatory Agency

Inclusion Criteria:

• Written informed consent, and assent where appropriate, obtained from the subject/from the subject's parent(s)/ Legally Acceptable Representative(s) (LAR).
• A male or female subject vaccinated with a first dose of GSK Biologicals' H1N1 pandemic influenza vaccine
• shortly (<24h) before being recruited in the study, and
• within a GP practice participating in the study and where the subject is registered.
• Subjects who the Investigator believes that they and/or their parent(s)/LAR can and will comply with the requirements of the protocol

Exclusion Criteria:

• Subjects already vaccinated with any other H1N1 pandemic vaccine before study enrolment.
• Child in care

The population studied will include individuals in priority groups currently considered for H1N1 pandemic vaccination. Subjects not pertaining to these priority groups can also be enrolled.