It is most common in the fall and winter. When a person with the flu coughs or sneezes, the virus becomes airborne and can be inhaled by anyone nearby. In most communities, it is school-age children who are the first to get the flu, and then they carry it home and to other group activities. Flu generally strikes 1 to 3 days after exposure to the virus. Common flu symptoms include sudden onset, fever and chills, cough, muscle and joint pain, headache, fatigue and weakness.
Some people also get a stuffy nose and sore throat.
A bad case of the flu will probably send a healthy adult or child to bed for 3 to 5 days. Afterwards, the person will recover fully, but cough and tiredness may persist for days or weeks. Nonetheless, the flu can be a serious illness. Each year, up to 40 million Americans develop the flu, and about 150,000 are hospitalized. During past epidemics in the United States, influenza and its complications have caused between 10,000 and 40,000 deaths.