MODEL RELEASED. Flu vaccination. Syringe about to be used by a general practice (GP) nurse to inject an influenza (flu) vaccine into the arm of a boy being comforted by his mother. Influenza vaccines contain dead influenza viruses. When injected, the vaccine stimulates the body's immune system to produce antibodies that protect against future infection by live influenza viruses. Vaccinations against influenza are usually short-lived because the virus mutates into new forms. Vaccination is mostly recommended for the elderly and the young, or anyone with respiratory or circulatory disease. The cotton swab is used to disinfect the skin and mop up any blood after the injection.