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    Expert Q&A — Why Is This Year's Flu Vaccine Ineffective? Or is it?

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    By Kathleen Doheny
    WebMD Health News

    Jan. 11, 2018 – Flu misery in the U.S. is increasing sharply, with widespread activity now reported in 46 states, according to the CDC. You could be one of those suffering, even if you got vaccinated. This year’s vaccine may be less protective than experts hoped — that’s still being determined.

    Meanwhile, WebMD asked William Schaffner, MD, professor of preventive medicine and infectious diseases at Vanderbilt University and a spokesperson for the Infectious Diseases Society of America, to shed light on the flu vaccine — why it isn’t perfect, why it’s still recommended and what improvements may be in the pipeline.

    WebMD: How effective is this year’s vaccine? Some are saying only 10%.

    Schaffner: The formal assessment has not yet been done because we are in the middle of the season. There are multiple viral influenza strains, and there is a dominant H3N2 strain [this year]. That is where we have heard all the discussion about being defective. That is because during the winter in Australia, our summer, they had a big H3N2 outbreak, essentially the same virus that has visited us now, and their effectiveness against H3N2 was only 10%.

    However, we vaccinate many more people than do the Australians. They have a limited set of recommendations on who should get vaccinated. Ours say if you are over 6 months, get vaccinated. So we vaccinate a much larger percent of the population. The CDC anticipates that like last year against H3N2 it will probably be between 10 and 35% effective.

    However, effectiveness estimates have to do with preventing the disease completely, and that is what we want. However, even if you get the vaccine and get sick, you are less likely to get the complications -1-have pneumonia, be hospitalized, or die.

    WebMD: Each year, the vaccine is developed to protect against strains experts predict will be prevalent. Why not widen that and take a shotgun approach?

    Schaffner: Actually it is a small shotgun.  The vaccine has protection against three or four strains and those are the ones that are assessed each year by expert committees to be the strains that are going to be the most common the coming winter. They have to predict 9 months in advance. It takes that long to make the vaccine, get it distributed.

    WebMD: What about the universal flu vaccine we’ve heard is under study?

    Schaffner: There are now some early clinical trials with universal vaccine candidates. Think of the influenza virus as a lollipop. The [viral] proteins that change are in the lollipop. The stick or the stalk is the same in all influenza viruses. There are now a number of researchers who are working to try to create a vaccine against the stalk [or stick] rather than the lollipop.

    WebMD: Realistically, when might this be available?

    Schaffner: It may be five years from now.

    WebMD: Why is there always more flu in the winter?

    Schaffner: Two reasons. When it’s cold we go inside and in enclosed spaces we have much more prolonged face to face contact. And that’s a circumstance where these respiratory viruses are readily transmitted.

    Second, if I am infected with influenza, I breathe out and I breathe out the virus.  It is surrounded by a little bubble of moisture. In the summer, when it is humid, that moisture does not evaporate and the microscopic particle is relatively heavy so it falls, gravity pulls it down. So it is not suspended in the air very long.

    However, in the winter, humidity is low, and when I exhale that particle, that droplet, the moisture evaporates. That means the viral particle is there, it’s much lighter, and it remains suspended in the air much longer. So it’s easier to get infected.

    WebMD: Is it too late to get vaccinated this year?

    Schaffner: It is late but not too late. Don’t linger. Do it this afternoon. It takes about a week to 10 days for your protection to build up. And then make a somewhat belated New Year’s resolution to be the first in line in September or October.

     

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