The aim of the present study is to assess the reactogenicity and immunogenicity of a thiomersal-free influenza vaccine. For comparison, a group of subjects is administered the standard formulation of Influsplit SSW® 2003/2004.

Inclusion Criteria:

• Subjects whose parents/guardians the investigator believes can and will comply with the requirements of the protocol
• Male or female children over 6 months of age at the time of vaccination, but who are not yet 6 years old.
• All children included in the study must never have been given a prophylactic influenza inoculation.
• Written consent to vaccination must be available from both parents or only the single parent after the parents/guardians have been briefed on the study in an understandable language.

Exclusion Criteria:

• Use of study or unlicensed medication or administration of a vaccine other than the study vaccine within 30 days preceding vaccination and/or during the study period until 30 days after administration of the second vaccine dose.
• Acute disease at the beginning of the study
• Acute clinically significant changes in the lungs, cardiovascular system, liver or kidney function, identified by physical examination or laboratory tests.
• Known allergic reactions that might have been caused by one or more components of the vaccine.
• Administration of immunoglobulins and/or other blood products within 3 months before the beginning of the study or planned administration during the study period.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.