Influenza, also known as the flu, is a contagious respiratory illness caused by flu viruses. Those with the flu may experience the following symptoms: fever/chills, cough, sore throat, runny/stuffy nose, muscle or body aches, headaches, fatigue, and vomiting and diarrhea. Most people will recover in a few days to less than two weeks, but some develop complications that may be life-threatening, such as pneumonia. High risk populations include people 65 years and older, people with chronic medical conditions (like asthma, diabetes, or heart disease), pregnant women, and young children. The flu is spread mainly by droplets made when people with the flu cough, sneeze, or talk. The best ways to prevent transmission are to get the seasonal vaccine and wash your hands regularly during the winter months.