A phase IV, open label, randomized, multicountry study to evaluate immunogenicity and safety of GSK Biologicals' seasonal (2010-2011) influenza vaccine Fluarix in children previously vaccinated with GSK Biologicals' H1N1 vaccine (Pandemrix)

*Subjects having previously been immunized with two 0.25 mL doses of Pandemrix (half dose), given at least 21 days apart, at the age of 6 months to 9 years inclusive at the time of first vaccination.
*Subjects having received the last dose of Pandemrix at least six months prior to study enrolment.
*Subjects who the investigator believes that parent(s)/Legally Acceptable Representative(s) [LAR(s)] can and will comply with the requirements of the protocol (e.g. completion of the diary cards, return for follow-up visits, be available for telephone/fax contacts).
*Written informed consent obtained from the parent(s)/LAR(s) of the subjects.
*Healthy subjects as established by medical history and clinical examination before entering into the study.
*Parent/LAR with access to a consistent means of telephone contact, land line or mobile, but NOT a pay phone or other multiple-user device (i.e., a common-use phone serving multiple rooms or apartments).

*Active participation in other clinical trials.
*Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of the study vaccine or planned use during the study period.
*Planned administration of any vaccine 30 days prior and 30 days after any study vaccine administration.
*Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within three months prior to enrolment in this study or planned administration during the study period. For corticosteroids, this will mean prednisone * 0.5 mg/kg/day, or equivalent. Inhaled and topical steroids are allowed.
*Acute disease and/or fever at the time of enrolment:
-Fever is defined as temperature * 37.5°C on oral, axillary or tympanic setting, or * 38.0°C on rectal setting.
-Subjects with a minor illness (such as mild diarrhoea, mild upper respiratory infection) without fever may be enrolled at the discretion of the investigator.
*Any confirmed or suspected immunosuppressive or immunodeficient condition based on medical history and physical examination (no laboratory testing required).
*Acute or chronic, clinically-significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by medical history and physical examination.
*Administration of immunoglobulins and/or any blood products within the three months prior to the enrolment in this study, or planned use during the study.
*Any known or suspected allergy to any constituent of influenza vaccines (including egg proteins or mercurial preservatives); a history of anaphylactic-type reaction to consumption of eggs; or a history of severe adverse reaction to a previous influenza vaccine.
*History of seizures (subjects who have had a single uncomplicated febrile convulsion in the past could be included) or progressive neurological disease.
*Subjects having received an H1N1v pandemic vaccine other than Pandemrix or having received the 2010/2011 seasonal influenza vaccine.
*Child in care.