What Is the Flu?

Influenza (say: in-floo-en-zah) is also called the flu. It's an infection that causes fever, chills, cough, body aches, headches, and sometimes earaches. The flu is caused by the influenza virus(say: vy-rus). A virus is a microorganism (say: my-croh-or-gah-nih-zum), which means it's so small that you can't see it without a strong microscope.

For most people, the flu is a drag, but it goes away in a week or two. But for some people, the flu can make them very sick. Those groups include:

• babies and kids younger than age 5
• people older than 50
• adults and kids who have health problems, such as diabetes and asthma

Anyone who's at risk of getting really sick needs to get a flu shot, or vaccine (say: vak-seen). People such as doctors and nurses also need the shot because they take care of sick people, and it's good for anyone who is around older people and younger kids to get the vaccine.
And now, experts say that all kids between the ages of 6 months and 18 years should get the flu shot. This is especially important for kids who have:

• heart or lung disorders, including asthma
• chronic diseases such as diabetes, certain kinds of anemia, or immune system problems, including HIV/AIDS

Flu vaccines are usually given in the fall, before flu season starts. Flu season means the months of the year when a lot of people have the flu and it's easy to catch it. It starts in November and usually ends in April.