It is a cold and dry winter morning. When you wake up, you feel that your throat hurts. You begin to sneeze and later you may cough. You must have a cold！Wait a moment. Could it just be a common cold or the flu(流感)that's been going around？
A cold gives you a runny nose and cough. But it's usually easy to deal with. Some people take medicine while others drink herbal tea or chicken soup. Usually you feel better after a week.
On the other hand, the flu can be much more dangerous. It usually gives you fever. Sometimes it can cause death. According to an American magazine, the worst flu killed about 50 million people from 1918 to 1919.
Don't worry. If you get a flu vaccine(疫苗), it can stop you from getting the virus(病毒).Flu vaccines work by giving the body a small number of flu viruses. This causes your body to develop antibodies(抗体). So next time you get the flu, the antibodies will help you.
The flu virus changes every few years. Therefore, there are so many types of flu, such as HlN1 and H5N1.The antibodies for one type of flu can't help us against all types of flu. That's why we need to get the vaccine every year.
However, good healthy habits may also help stop you developing a cold or flu. Washing your hands often helps stop you from getting viruses. It is also important to get regular exercise and eat healthy food. All these can help you strengthen(增强)your immune system(免疫系统).
