nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
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Thursday, October 7, 2010

Another Flu Vaccine Myth Bites The Dust

The media went nuts a few months ago about Sweden looking into cases of narcolepsy after taking the H1N1 vaccine.

Narcolepsy is a chronic sleep disorder.  The most common symptom is excessive daytime sleepiness, in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school.  It's a complex problem with other features we don't need to go into:  cataplexy, hypnagogic hallucinations, etc, even insomnia.  We understand the syndrome poorly, but there's evidence for a genetic component, and some type of autoimmune phenomenon.

Once announced, the vaccine alarm spread throughout Europe, with some countries suspending one particular product.  Just Google "vaccine" and "narcolepsy" to see the dozens of articles about it.

Now comes word that although there were a handful of cases of narcolepsy diagnosed in people who had taken the vaccine, there were just as many who were diagnosed with the disease that had not received the shot.

For Onion Peelers,
Turns out that Sweden gave 6 million doses to its population of 9.3 million.  There were six cases of narcolepsy diagnosed in children; in that group only two had received the vaccine.  Of 10 adult cases of narcolepsy, half had taken the shot, half had not.  Ergo, what you might expect from chance alone.

This is a classic case of the Texas Sharpshooter fallacy, and one commonly at work when people falsely perceive an increase in some adverse event.

The fallacy goes like this:  our crafty Texan fires a number of shots at the side of a barn, then goes up and paints a bullseye around all the bullet holes, and claims to have scored a bullseye with every shot...and therefore is a sharpshooter.

Explained like this, everyone can say "Well, sure, that's fallacious reasoning."  But then, when several people with an unusual illness or adverse reaction pop up in a location, most of us forget all about the fallacy and assume that there's an outbreak ("danger, Will Robinson.")

In Sweden, somebody happened to notice a couple of cases of childhood narcolepsy in vaccinated children, and isolated that data from the total environment (in the same way the  sharpshooter drew his bullseye).  Once the statistics were in, people could see that there were just as many cases, or more, of narcolepsy without the vaccine than in association with it.

Investigating isolated observations of disease occurrence is a good thing.  Ignoring input is foolhardy.  Rarely, it leads to useful information of a real food poisoning from a widely atttended picnic.  Most often it's a red herring.  But you have to ask yourself about plausibility:  is there a conceivable link between vaccines and narcolepsy?  Well it's "conceivable" (as is the existence of martians), but not a known connection for any other vaccine.  And even if conceivable, how much faith should we put into an analysis of two or three cases of a rare disease?

This fallacy is a weakness built into human reasoning that probably had some survival value in the pre-historic period when individuals had no idea how or why things happened to them.  An integral part of the fight-or-flight reaction, maybe:  better to assume the worst and think it through later.

The epidemiology literature is littered with examples of panic over episodes like this.

If you hear of unlikely associations, it's best not to don your 10 gallon hat, grab a rifle and head for the barn.

Doc D


whitney blane said...

great article here. im continuing my research for my daughter. here's another article i found on the flu shot

Bea Smith said...

Cylert (generic: Pemoline) was an exceptionally effective treatment for Excessive Daytime Sleepiness. I used it daily for many years. Unfortunately, it's no longer on the market.

Quite by accident, we came across a non-prescription compound originally intended to treat drug addiction (!) but which is the only Cylert substitute we've found that works for sufferers of Excessive Daytime Sleepiness.

Anyone who's interested in the details is welcome to visit our site.

Doc D said...

As a preventive medicine specialist, I believe that vaccines are the 2nd most important development in human history, in terms of lives saved. Like every single medicine, they have adverse reactions in a few people. As a child, I remember vast numbers of kids with polio--iron lung wards across the nation. Now? Gone. Why? Vaccine.

(The #1 disease prevention development in history was the sanitation movement in the 19th Cent. #3 is antibiotics.)

My son used Cylert for ADD. It worked well. The withdrawal from the market was politics, combined with fears over liver toxicity. Over 30 years and millions of patients there were 21 cases of liver failure. Compared to some other drugs, that's actually pretty safe, and it was never determined whether those rare cases were OD's or something else.

Our health care system is driven by belief as much as by the science.

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