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    Flu Season: What to Know This Year

    Editor's Note: This story was updated Dec. 8, 2017.

    How bad will the flu season be this year?

    Some public health officials say they are seeing an uptick in flu this month. And at the same time, the flu vaccine may not be that effective.

    The most common vaccine circulating right now is H3N2, according to CDC. That's the same virus that was also found in Australia for their flu season. Their vaccine -- the same one we have -- was only 10% effective against H3N2 there.

    But CDC epidemiologist Lynnette Brammer said a similar vaccine was 43% effective against the same virus in last year's flu season and 48% overall. Other types of flu viruses are circulating as well, she said.

    Flu activity is widespread in Louisiana, Georgia, Oklahoma, Arkansas, Mississippi, Virginia and Massachusetts. The CDC updates its map weekly with the most recent figures, which you can see here.

    Flu activity “has been increasing since the beginning of November,” said CDC spokesperson Kristen Nordlund.

    In Arizona, a family reported that Alani Murrieta died last month from flu that became pneumomia. The 20-year-old was the mother of 2-year-old and 6-month-old boys. Health officials don’t track adult deaths from flu.

    “We’re seeing more cases earlier in the season than we typically do,” says Nicole Capone, a public information officer for the Arizona Department of Health Services.

    Officials will continue to watch how well this year’s vaccine works.

    Two types of flu viruses, A and B, infect humans, and there are many strains of each. In order to have flu shots ready for flu season, experts have to decide, months in advance, which strains to include in the vaccine. Because strains can change quickly, the vaccine is not always a good match.

    Even when the vaccine is a good match, the way it is produced may limit how well it works.

    In November, Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, along with experts from the World Health Organization and Australia, warned that the way most flu shots are produced in the U.S.—by growing their active ingredients in chicken eggs—may diminish their effectiveness.  Because the vaccine strains have to be changed slightly to allow them to grow in eggs, they may lose their ability to help the body fight the infection. Egg production may be one reason this year’s flu shot was only 10% effective in Australia.

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