Influenza (flu) is a contagious respiratory disease caused by influenza viruses that infect the respiratory tract (nose, throat, and lungs) in humans. The symptoms and complications of flu are more severe than common cold. The symptoms associated with influenza may include... fever, headache, malaise, cough, sore throat, nasal congestion, and body aches. Influenza vaccine can prevent illness and death caused by the influenza virus. Influenza vaccine can be administrated to both young and old patien更多