Influenza (also called flu) is caused by influenza viruses that infect the nose, throat, and lungs. Most experts believe that flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouth or noses of people who are nearby. The influenza virus can then infect those people. You can also get flu by touching a surface or object that has flu virus on it and then touching your mouth, eyes, or nose.
Flu can cause mild to severe illness. In some cases, flu can lead to death. The best way to prevent flu is by getting a flu shot every year!