Immunogenicity and Safety Following a Single Dose of Influenza Vaccines in Healthy Children Who Received Either One or the Other Vaccine (an Adjuvanted Sub-unit Influenza Vaccine and a Non-adjuvanted Split Virion Influenza Vaccine) in the Previous V70P2 Study

Inclusion Criteria: * children up to 48 months of age, who received both doses of one of the two study vaccines in the previous V70P2 trial, whose parents/legal guardians have given written informed consent prior to study entry, * in good health as determined by:medical history, physical examination, clinical judgment of the investigator. Exclusion Criteria: * Experience of a severe acute infectious disease in the month prior to study start or experience of a mild acute infection disease in the week prior the study start; * Any severe acute respiratory disease and infection requiring systemic antibiotic or antiviral therapy ongoing or resolved within 15 days prior to study start (chronic antibiotic therapy for urinary tract prophylaxis is acceptable); * Fever (defined as axillary temperature ≥ 38.0°C/rectal temperature ≥ 38.5°C) within the 7 days before enrolment; * Any serious disease including, for example:cancer,autoimmune disease (including rheumatoid arthritis),diabetes mellitus,chronic pulmonary disease,acute or progressive hepatic disease,acute or progressive renal disease; * Known or suspected impairment/alteration of immune function, for example, resulting from:receipt of immunosuppressive therapy (corticosteroid - except topical or inhaled steroids - or cancer chemotherapy),receipt of immunostimulants,receipt of parenteral immunoglobulin preparation, blood products, and/or plasma derivatives within the past 3 months and for the full length of the study,high risk for developing an immunocompromising disease; * Bleeding diathesis; * History of hypersensitivity to any component of the study medication or chemically related substances; * History of any anaphylaxis, serious vaccine reactions, or allergy to eggs, egg products or any other vaccine component; * Laboratory confirmed influenza disease in the past 6 months; * Surgery planned during the study period; * Receipt of another investigational vaccine or any investigational agent within 30 days prior to study start. All routine vaccines should be given according to local recommendations: routine vaccines or any other vaccines not foreseen in the protocol can be given after the active trial phase (i.e. 4 weeks after last vaccination in the respective season) has been concluded; * Participation to another trial of an investigational agent within 90 days of enrolment; * Any condition which, in the opinion of the investigator, might interfere with the evaluation of the study objectives.