Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can spread through contact with respiratory droplets produced when an infected person coughs, sneezes, or talks. The flu can cause various symptoms, including fever, chills, cough, sore throat, runny nose, muscle aches, and fatigue.
Getting the flu vaccine is the most effective way to prevent the flu. The flu vaccine is made with inactivated or weakened flu viruses, which help the body develop immunity to the flu without causing illness. It is recommended that everyone 6 months of age and older get a flu vaccine annually.