Influenza (flu) viruses change continuously, therefore also the parts of viruses used in influenza vaccines can vary from year to year. The current study is a phase III A clinical trial with a commercially available vaccine (Influvac®) supplied in pre filled syringes. The objective of this study is to investigate the immunogenicity and safety and tolerability of the changed influenza vaccine virus composition in two groups of subjects in good health: subjects aged >= 18 and <= 60 years and subjects >= 61 years of age (elderly).

Inclusion Criteria:

• Willing and able to give informed consent and able to adhere to all protocol required study procedures.
• Men and women aged ≥ 18 and ≤ 60 years or ≥ 61 years of age at the day of study vaccination.
• Being in good health as judged by medical history, physical examination (if needed) and clinical judgment of the Investigator

Exclusion Criteria:

• Known to be allergic to eggs, chicken protein, gentamicin or any other constituent of the vaccine.
• A serious adverse reaction after a previous (influenza) vaccination.
• Presence of any significant condition that may prohibit inclusion as determined by the investigator.
• Seasonal or pandemic influenza vaccination or laboratory confirmed seasonal or pandemic influenza infection within the previous six months before study vaccination or planned vaccination during the study period.
• A history of Guillain-Barré syndrome or active neurological disease.