Cold weather, central heating, and falling leaves—all these things mean that flu season has arrived. And you shouldn't take flu lightly. Flu season comes every year from October to April. This year has been especially bad, according to the US Centers for Disease Control and Prevention (美国疾病防控中心 CDC).

The flu is an illness caused by the influenza virus. It is different from the common cold in that it can strike suddenly—and it is much more serious .The flu can cause serious dehydration(脱水) and liver (肝脏)damage ,both of which can kill people.

    The flu is especially dangerous for children and elderly people, since they have weaker immune (免疫) system. As of April 20, 142 children in the US had died from the flu during this flu season, according to CDC.

    These deaths are not limited to the USA. In China, many people die from the flu each year as well. An elderly man in Beijing died from the flu this season, which led to a wide discussion online. The man's family didn't know how serious the flu was, just like many others who don't understand the flu very well.

What can you do to keep the flu away? Hygiene is important — take a shower every day and wash your hands often. Do not spend time around people who have the flu. And if you can, get a flu vaccine — this is a type of special medicine that can help prevent the flu. All of these things can keep you safe during flu season. If you are stick with the flu, stay home to prevent spreading it to others.