Influenza Information   Influenza, commonly called "the flu," is a contagious respiratory illness caused by influenza viruses. Infection with influenza viruses can result in illnesses ranging from mild to severe with potentially life-threatening complications. An estimated 10% to 20% of US residents get the flu each year, an average of 114,000 people are hospitalized for flu-related complications and 36,000 Americans die each year from complications related to the flu. Influenza viruses are unique in their ability to cause sudden, pervasive infection in all age groups on a global scale. The national response to an influenza pandemic will largely reflect the ability of states and local areas to respond. An influenza pandemic would require an immediate and coordinated response from the District of Columbia's Department of Health (DOH), the medical community, and other stakeholders to maintain the health and wellbeing of residents, workers and visitors to the District of Columbia.