Some key things to know about the flu season:
THE SITUATION: The annual flu season hit about a month early this year, and illness is now widespread in 47 states. Many cases are caused by a flu strain that tends to make people sicker. But so far experts say it's too early to know whether this will end up being a bad season. Maybe not: There are signs the flu may have already peaked in a few states, though it's too early to tell for sure, health officials say.
THE VACCINE: This season's vaccine is well matched to the circulating strains, and there's still some available. It is 62 percent effective, according to government study results released Friday, which is pretty good for a flu vaccine. Health officials are urging people to get vaccinated; it's recommended for everyone 6 months or older.
THE DEFENSE: Besides getting a flu shot, wash hands with soap and warm water, and avoid touching your eyes, nose and mouth. Keep away from sick people.
THE TREATMENT: Most people will get a mild case and can help themselves and protect others by staying home and resting. But people with severe symptoms should see a doctor. They may be given antiviral drugs or other medications to ease symptoms.
COLD OR FLU?: Influenza is not the only bug making people sick. The cold virus and a nasty stomach virus are also going around. It can sometimes be hard to tell the difference, but cold symptoms include stuffy or runny nose, sore throat and sneezing. Flu usually involves fever, along with chills, headache and moderate-to-severe body aches and tiredness. Symptoms can come on rapidly, within three to six hours.