The exact magnitude of the benefit of influenza vaccine among elderly individuals is subject of considerable debated. Existing vaccine effectiveness estimates come mostly from observational studies. Annual influenza vaccination, that is considered the most effective strategy to prevent influenza by the World Health Organization, is recommended for elderly in many developed countries.
For influenza vaccination of adult ≥65 years of age, high-dose inactivated influenza vaccine is recommended which has previously been shown to be more immunogenic and modestly more effective at preventing influenza infection than the standard-dose vaccine. In a study of United States Medicare beneficiaries ≥65 years of age, the high-dose vaccine was more effective than the standard-dose vaccine in preventing post-influenza death during the 2012-2013 influenza season, a season when circulation of H3N2…
