Prevention of influenza, especially in those who run an increased risk of associated complications. The use of Influvac should be based on official recommendations. Vaccination is particularly recommended for the following categories of patients, depending on national immunization policies: Persons ≥65 years, regardless of their health condition; adults and children with chronic disorders of the pulmonary or cardiovascular systems, including asthma; chronic metabolic diseases eg, diabetes mellitus; chronic renal dysfunction; immunodeficiencies due to disease or immunosuppressant medication (eg, cytostatics or corticosteroids) or radiotherapy; children and teenagers (6 months to 18 years) who receive long-term acetylsalicylic acid-containing medication, and might therefore be at risk for developing Reye's syndrome following an influenza infection.