Between 5% and 20% of the American population catch the flu each year.  But what is the flu and how can we prevent the flu from passing from one person to another?

The flu is a respiratory infection caused by viruses.  The flu is usually more serious than the common cold, because of the severity of the symptoms.  In fact, the flu can kill millions of people during pandemics (such as the 1918 pandemic that killed 50 million people).  You usually become infected with the flu when the virus enters your mouth or nose. Typically, the flu lasts from 1 to 2 weeks and is passed through the air.