Flu season occurs annually in countries that have weather in the winter. Although the influenza virus alive throughout the world in all four seasons, seems to have its greatest impact on humans the winter. Scientists are not sure why. They it’s because in the winter people are indoors close together for longer periods of time. Also, virus might be able to live longer and stronger in colder weather. Finally, indoor air can up the mucous that helps protect people from virus.

In the U.S., the virus is not to sneeze at. It kills about 36,000 people (most of them elderly). It also causes almost ,000 people to end up in a hospital bed .

Scientists develop a preventive flu shot for people take as winter begins. This shot is not to prevent flu; scientists can only guess at virus might be the most dangerous in the season. The shot protects against only that particular . For those who do not get the shot, spreads among them easily. It takes only a , a cough, or a touch. Victims frequently get from shaking hands, opening doors, or handling money.

infected people will have a fever, sore throat, cough. But the symptoms are often mild and for only a week. For many others, however, can be so severe and prolonged that victims up in bed for weeks, or in the , or in the cemetery.