Centers for Disease Control and Prevention
Centers for Disease Control: The Influenza (Flu) Viruses
Read about the different types of flu viruses, and learn how the flu can spread and change. Learn how many people are hospitalized due to the influenza virus every year and more.
World Health Organization
World Health Organization: Influenza
This competent site explores the following topics: overview, the virus, pandemic influenza, transmission, diagnosis, prevention, and treatment. Related links are provided for additional information.