Prevention is the best influenza protection

For years, we have heard (and I have often said) that an average of 36,000 Americans die from influenza annually.

This figure is based on data from 1990-1999. Now the CDC is telling us that the range of annual deaths is too wide to continue using that single number. Based on a lot more seasons (1976-2007), the average is closer to 24,000 with a range of about 3,300 to 49,000 influenza deaths per year.

This wide range is not surprising.

The virulence of influenza viruses varies substantially depending on the dominant circulating strain. Beyond that, you don’t need me to tell you all the other factors that affect mortality – virus communicability, age-related attack rates, etc.

But how do we explain all of this to our patients?

How do we balance how much data are too much, too little and – yes, just right?

In this age of information overload, it is important that every healthcare professional gives good, solid, scientific information to their patients. But that does not mean we have to go into detail about every piece of data available.

In this case, why talk about data going back 34 years to 1976? And is there really any value to discussing the “low year” in CDC’s range?

It was more than two decades ago-3,349 deaths in the 1986-1987 season.

Our population was smaller and demographically much younger then.

While we don’t have to talk specific numbers, we do have to admit this truth to our patients – we don’t know exactly how many people die from influenza every year.

Flu deaths are hard to count. Influenza isn’t always listed as the cause of death, but is often a factor in deaths attributed to other underlying causes. But here are some things we do know and these are the messages I’ll be focusing on with my patients: Any death that is preventable should be prevented.

Even in the mildest year, the people who die are moms, dads, sons, daughters, aunts, uncles, grandparents and friends. If I cared about someone who died, it wouldn’t make much difference to me if they were one of 3,000 or 50,000. Let’s act on what’s certain. Flu will come every year and it will kill every year. Our best protection is vaccination. Predictions won’t save us. Prevention will.

William Schaffner is Professor and Chair, Department of Preventive Medicine, Vanderbilt University School of Medicine, and blogs at Infectious Disease News.

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  • Dr.Z

    I agree having a single number representing the average annual influenza fatalities is as meaningful as the range of annual MLB batting average from 1990 – 1999. However, expanding the span to 1976 – 2007 and then reporting a range showing a 15-fold diversion is equally meaningless unless accompanied by the rationale explaining deviation beyond three standard deviation.

    All in all … an interesting gee-whiz number PCPs can share with patients … is now being hijacked by nerds without creating any value parameter which orients patients to seek immunization.

  • http://jflahiff.wordpress.com Janice Flahiff

    I for one will definitely be getting a flu shot this year, to help prevent it in myself and others. While herd immunity may not be approached, I am not going to be part of the problem!

    However, I am a bit puzzled by a blog item (written by a nutritionist) “Why “Herd Immunity” is Moot in Seasonal Flu or Swine Flu” [http://www.wellsphere.com/general-medicine-article/why-herd-immunity-is-moot-in-seasonal-flu-or-swine-flu/810092]. It seems to make scientific claims against herd immunity (as there is no virus-vaccine match, at risk groups not protected by the vaccine, A Cochrane report stating that in healthy adults “lu vaccination of a population would prevent 0.1 per cent of a working day lost”)

    Also, “…The shot has never worked” [http://www.wellsphere.com/general-medicine-article/it-s-seasonal-flu-shot-season-but-the-shot-has-never-worked/810093] .. cites Cochrane and seemingly peer reviewed articles to “prove” that flu shots do not work for babies, children with asthma,adults, or the elderly.

    I am wondering if the blog author is making an effective argument, and has objectively weighed all evidence, pro and con. Or if I am getting all worked up over something trivial.

    Any reply from any reader here would be much appreciated.
    Am hoping to get some additional objective evidence on herd immunity & influenza for a blog item.. Or good related item to quote in my bog.

    Thank you for considering a reply. Much appreciated.

    • gzuckier

      Well, I saw that Cochrane review, and I recall that their metastudy does seem to show no drop in mortality consistent with vaccination among the elderly; the hypothesis, which seems at least halfway reasonable, is that if your immune system is too weak to protect you from becoming fatally ill from the flu, it’s too weak to muster a competent immune response from a flu vaccination.

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