Influenza, commonly called "the flu", is an infection of the respiratory tract caused by the Influenza virus. Compared with most other viral respiratory infections, such as the common cold, Influenza infection often causes a more severe illness. Typical Influenza illness includes fever and respiratory symptoms, such as cough, sore throat, runny or stuffy nose, as well as headache, muscle aches, and often extreme fatigue. Although nausea, vomiting, and diarrhea can sometimes accompany Influenza infection, especially in children, these symptoms are rarely the primary symptoms. Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. In an average year, Influenza is associated with more than 20,000 deaths nationwide and more than 100,000 hospitalizations. Flu-related complications can occur at any age; however, the elderly and people with chronic health problems are much more likely to develop serious complications after Influenza infection than are younger, healthier people