Influenza is a common infectious disease that affects many people. Most people with influenza recover quickly, but elderly people and those with chronic medical conditions are at higher risk of complications and even death. Influenza vaccination rate refers to the number of people aged 65 and older who have received an annual influenza vaccination, divided by the total number of people over 65 years of age. This indicator is measured as a percentage of the population aged 65 and older who have received an annual influenza vaccine. The data come from administrative sources or surveys, depending on the country.