Up to 5.4M people in U.S. already have had the flu this season

Up to 5.4 million people in the United States already have been sick with the flu this fall, according to data compiled by the Centers for Disease Control and Prevention. The agency also estimates that flu has caused as many as 55,000 hospitalizations and 4,600 deaths from Oct. 1 through Dec. 2.

As flu season progresses, usually peaking between December and February, the CDC plans to update its tally of flu-related cases weekly. The flu, or influenza, is a highly contagious respiratory infection caused by viruses that spread from person to person, often via droplets expelled through coughing or sneezing.

The flu, like colds and other respiratory illnesses, is more common in cold weather as people tend to spend more time indoors, where viruses can pass more easily from person to person. Also, health experts believe the flu virus survives better in cold weather and cold, dry air weakens people’s resistance.

Common symptoms of influenza include a cough, sore throat, fever, headaches and fatigue. Influenza is not the same as the “stomach flu” (gastroenteritis), which is a stomach and intestinal infection that causes diarrhea, nausea or vomiting. Illness from influenza is usually mild, but it can be serious (and sometimes deadly), especially for the elderly, newborns and those who have a chronic illness or are pregnant.

Flu symptoms generally last three to five days, although coughing and tiredness may linger for a few weeks. Treatment usually involves rest and drinking lots of fluids, but antiviral medication may be prescribed for more severe cases.

Prevention efforts focus on annual flu shots, recommended for everyone 6 months and older and updated each year to cope with changes in the influenza virus. In the flu season a year ago (fall 2022 to spring 2023), some 31 million U.S. residents contracted the flu, and 21,000 died of it, according to the CDC, which classified that span as a flu season of “moderate severity.”