Flu season is officially here, according to the Centers for Disease Control and Prevention.
As of Jan. 3, all 50 states have reported confirmed cases of flu, and 25 states reported widespread flu activity, the CDC said.
The percentage of patients visiting the doctor for flu-like symptoms also increased in recent weeks, from about 2 percent the week ending Dec. 7 to 4.3 percent the week ending Jan. 3.
These and other measures of current flu activity are a good sign that flu season is "well under way," a statement from the CDC said. Flu activity has been most intense in the south-central and southeast part of the United States, the statement said.
The rate of flu hospitalization has also increased slightly in recent weeks, and is now at 5.8 hospitalizations per 100,000 people in the population. (Around this time last season, the rate was 13.3 hospitalizations per 100,000 in the population.)
The CDC recommends flu vaccination for everyone ages 6 months and older.