The annual influenza outbreak has reached widespread levels in 43 states - up from 36 states a week ago.
New figures from the Centers for Disease Control and Prevention show that six more children have died from flu, including three kids in Tennessee, making for 21 pediatric deaths this flu season.
Flu activity typically waxes and wanes during the coldest months. While the nation reached an epidemic level of flu last week, the portion of weekly flu-and pneumonia-related deaths - 6.8 percent of all deaths - dipped below the epidemic threshold for the first week of January.
Flu generally hits hardest in the very young and the very old. Depending on the season and the strain, it can kill anywhere between 4,000 and 50,000 people each year in the United States.
CDC still says people should get a flu vaccine to guard against infection. Frequent hand washing is also a great defense. Flu is typically spread via close contact with an ill person who is sneezing or coughing, or by touching the expelled droplets, then placing your fingers into your eyes, nose or mouth.
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