Influenza (the flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccination each year. Some people, such as older people, young children, and people with certain health conditions, are at higher risk for serious flu complications.

More Influenza Information from the CDC »

Pandemic Influenza

What is an Influenza Pandemic?

An influenza pandemic occurs when a new influenza virus emerges for which people have little or no immunity, and for which there is no vaccine. The disease spreads easily from person-to-person, causing serious illness, and can sweep across the country and around the world in very short time.


Avian Influenza

Avian (bird) flu is caused by influenza A viruses that occur naturally among birds. Wild birds worldwide carry avian influenza viruses in their intestines, but usually do not get sick from them. Avian influenza is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them.