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June 25, 2019

The longest flu season in a decade, charted

Daily Briefing

    This year's influenza season lasted 21 weeks, making it the longest flu season in a decade, according to a CDC report released Friday.

    Infographic: How to avoid the flu when you fly

    The report breaks down the 2018-2019 flu season's effect from Sept. 30, 2018, to May 18, 2019. The report includes details on the number of flu cases, doctor visits, and hospitalizations.

    2018-2019 flu season the longest in a decade, CDC finds 

    Overall, the researchers found this year's flu season was "moderate[ly] severe," but it lasted longer than any other flu season in the past 10 years, according to CDC. CDC measured the length of the flu season by tracking how long flu-like illness was above baseline. This year, that period lasted 21 consecutive weeks.

    The researchers noted the number of cases of flu-like illnesses reported during the flu season began increasing nationally in November 2018 and reached a peak in mid-February. The number of cases then dropped below baseline levels in mid-April. The researchers also found the number of U.S. jurisdictions reporting "widespread" flu activity reached a peak the week ending on Feb. 23, 2019, when a total of 50 jurisdictions reported "widespread" activity

    The researchers found a majority of cases involved influenza A viruses and only a few involved influenza B viruses.

    Overall, the researchers estimated between 37.4 million and 42.9 million U.S. residents were diagnosed with the flu from Oct. 1, 2018, to May 4, 2019, leading to at least 17.3 million medical visits and 531,000 hospitalizations during that time period.

    The researchers noted flu-related hospitalizations peaked during the week ending on March 16. The researchers estimated a total of 18,847 flu-related hospitalizations occurred from Oct. 1, 2018, to April 30, 2019. Of those hospitalizations, 47% involved adults 65 and older.

    The researchers found the percentage of outpatient visits for flu-like illness remained above the national baseline of 2.2% from November 2018 to the week ending on April 20.

    According to the report, between 36,400 and 61,200 flu-related deaths occurred during the 2018-2019 flu season. The researchers found 116 pediatric deaths have been reported this flu season. Last year's flu season led to 50 million cases, almost one million hospitalizations, and 80,000 deaths (Kommers, Becker's Clinical Leadership & Infection Control, 6/21; CDC report, 6/21; CDC, "FluView," accessed 6/24).

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