Introduction

What is Influenza?

Influenza is a very contagious viral infection that affects the air passages of the lungs. It causes a high fever, body aches, a cough, and other symptoms. It is one of the most severe and common viral illnesses of the winter season.

Influenza is commonly called the flu, but it's not the same as stomach "flu" viruses that cause diarrhea and vomiting.

The flu is caused by influenza viruses that infect the nose, throat, and lungs. These viruses spread when people with flu cough, sneeze or talk, sending droplets with the virus into the air and potentially into the mouths or noses of people who are nearby.