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This article was last reviewed on
This article waslast modified on
January 26, 2018.

The Centers for Disease Control and Prevention (CDC) is reporting particularly severe and widespread influenza (flu) in most of the U.S. this 2017-2018 season. The most recent data show that flu cases sharply increased the last week in December. Across the country, the percentage of people seeking care for influenza-like illness was 5.8%, which is more than double the national baseline of 2.2%.

Between October 1 and December 30, 2017, almost 14 out of 100,000 Americans were hospitalized due to influenza. Adults 65 years old and older had the highest rates of hospitalizations, with adults 50 to 64 years old and infants and children up to 4 years old having the next highest rates.

In mid-December, the CDC published a report with new estimates that showed an increase in the annual number of worldwide deaths due to seasonal flu-related illnesses. Approximately 291,000 to 646,000 people worldwide die from seasonal influenza-related illness each year, up from the previous estimate of 250,000 to 500,000 people.

Though flu can be serious, most people recover within a few days with supportive treatment, such as getting sufficient rest and drinking plenty of fluids. Some people, however, have a higher risk of serious complications from flu, including pneumonia. Pregnant women, the very young, the elderly, and people with underlying medical conditions should consult their healthcare practitioner as soon as they experience symptoms so they can receive treatment and can be monitored closely. Signs and symptoms include fever, chills, aches, headache, cough, sore throat, runny or stuffy nose, weakness and fatigue, and sometimes vomiting and diarrhea.

While the flu is usually most serious for young children and the elderly, people of all ages can experience severe illness. All individuals should seek care right away when they experience serious symptoms, such as difficulty breathing, shortness of breath, chest pain or discomfort, dizziness, confusion, and prolonged or severe vomiting.

It is not always easy to tell the difference between flu symptoms and those due to a serious cold. A healthcare practitioner may opt to test a patient, especially one at risk, to help make a diagnosis. The most accurate influenza tests, according to the CDC, are molecular tests that detect the genetic material of the virus in respiratory samples. Rapid molecular tests that provide results in 15 to 30 minutes with high sensitivity and specificity may be available at the point of care (POCT), such as clinics and physician offices. If POCT molecular tests are not available, samples may be sent to a clinical laboratory, where results of the molecular tests are available within several hours. There are non-molecular flu tests that can also be performed at the point-of-care or in a laboratory, but they are not as sensitive or specific.

Even with the availability of rapid tests, the CDC is encouraging healthcare practitioners to start patients with suspected flu on antiviral treatments as soon as possible after signs and symptoms appear. Treatment is most effective within 48 hours after the onset of illness and should not be delayed while waiting the few hours for results.

For individuals who have not yet received their flu shot, there is still time to do so, according to the CDC, since there are still several weeks left in this flu season. The agency recommends everyone 6 months or older get a flu shot each year to provide protection against the virus and to minimize the severity of symptoms if they do become ill.

View Sources

(December 27, 2017) Centers for Disease Control and Prevention. Health Advisory, Seasonal Influenza A(H3N2) Activity and Antiviral Treatment of Patients with Influenza. Available online at https://emergency.cdc.gov/han/han00409.asp. Accessed January 12, 2018.

(December 13, 2017) Centers for Disease Control and Prevention. Press Release, Seasonal flu death estimate increases worldwide. Available online at https://www.cdc.gov/media/releases/2017/p1213-flu-death-estimate.html. Accessed January 12, 2018.

(January 10, 2018) Centers for Disease Control and Prevention. Influenza (Flu). Available online at https://www.cdc.gov/flu/index.htm. Accessed January 12, 2018.

(January 5, 2018) Centers for Disease Control and Prevention. Situation Update: Summary of Weekly FluView Report. Available online at https://www.cdc.gov/flu/weekly/summary.htm. Accessed January 12, 2018.