Purpose
- Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. Some people, such as people 65 years and older, young children, and people with certain health conditions, are at higher risk of serious flu complications.
Overview
There are two main types of influenza (flu) viruses: types A and B. The influenza A and B viruses that routinely spread in people (human influenza viruses) are responsible for seasonal flu epidemics each year.
The best way to reduce the risk of flu and its potentially serious complications is by getting vaccinated each year.
Burden of Influenza
Each year CDC estimates the burden of flu in the United States using modeling to estimate the number of flu-associated illnesses, medical visits, hospitalizations, and deaths that occur during a given season.
Resources
Key Facts About Influenza (Flu)
Flu and flu vaccine
Flu Season
When flu season occurs in the United States
Understanding Influenza Viruses
Learn more about different types of influenza viruses and how these viruses can change over time.