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The Power of Coincidence and How it Can Lead Us Astray

Posted on Tue, Dec 24, 2013 @ 06:00 AM

Katie Couric did a segment on her talk show on December 4th about the human papilloma virus (HPV) vaccine. The promo for that show had one graphic that said ‘HPV Vaccine Controversy’ and another that said ‘Potentially Dangerous’. I’ll leave the broader critiques to others (see Matthew Herper and Seth Mnookin for two good ones). Couric’s show was a biased view of the HPV vaccine that hysterically exaggerated the vaccine’s risks and gave very little time to more reasoned and balanced viewpoints.


HPV Vaccine


Couric’s program featured a mother whose daughter became ill and died 18 days after she received the vaccine. Another woman was featured who became ill soon after receiving the vaccine. These two examples, neither of which were conclusively tied to the vaccine, illustrate a phenomenon I like to call the Power of Coincidence. If something bad happens, like serious illness or death, our natural reaction is to try to identify the cause. Clearly, knowing the cause of something is the most effective way to address it. But what if the cause is not obvious, or if it is an undiagnosed condition that only crops up long after the original causative event took place?

There are plenty of examples of this. For instance, autism is generally thought to be caused by mutations that happen during brain development before birth, but most children are not diagnosed until after age one, which is when symptoms associated with autism commonly appear. In a previous blog I described a condition called Dravet Syndrome which is caused by a mutation present before birth that is triggered by a fever after birth. Lastly, despite lots of research, there’s really no clear cause of Sudden Infant Death Syndrome.

So if the actual cause is not obvious, it is only natural to try to find, sometimes desperately, something to blame. I can completely identify with this and have experienced this situation in my own family. The doubts that take over in a parent’s mind about what they could have done to prevent their child’s health issues are very powerful.

One thing that can attract people’s attention in this kind of case is, as you might have guessed, vaccine injections. There are several reasons for this which combine to create fertile ground for people’s imaginations to run wild. You’re injecting something into a helpless infant or small child, typically causing them some pain. The vaccines are produced by large pharmaceutical companies, of which many people have a negative perception. The positive effects from vaccines, prevention of disease, are not immediately obvious. Many of them protect against diseases that most of us have very little knowledge of, like diptheria. Of course, the reason we don’t know much about these conditions is because vaccines have made them virtually nonexistent.

But probably the biggest reason people latch onto vaccines is because they’ve heard a story about somebody who got a vaccine and then had a health issue soon after. Jenny McCarthy has widely claimed that vaccines caused her son’s autism, of which he was allegedly later cured. The since-discredited study by Andrew Wakefield linking autism to vaccines is still widely passed around as truth. And of course, those stories that Katie Couric told on her show.

But let’s think about one case Couric mentioned. Imagine that something bad happened to a child with no obvious cause but within 18 days of being vaccinated. That’s another story that could be told of vaccines causing harm; a story that could be widely spread and even turn into a lawsuit. And now remember that children can get vaccinated up to seven times before they reach the age of 18 months. So any event that happens has an almost 25% chance of happening within 18 days of a vaccination (7 vaccinations * 18 days = 126 days, 126 / (1.5 * 365) = 23%). That’s no small chance, and given that there are about 10 million children under age two in just the United States, even a rare medical event that happens to only in one child in 100,000 would happen within 18 days of a vaccination about a hundred times each year. The people this happened to could become believers, like the people Couric highlighted, and have a powerful story to tell others. And sadly, sometimes be given a forum on national television.

Couric published a blog on December 10th that was a semi-apology for her treatment of the HPV vaccine on her show. She wrote “there's no question that vaccination is highly effective” and, in reference to the two stories she told on her show, “there is no definitive proof that these two situations were related to the vaccine.” Unfortunately, I’m sure Couric’s blog readership is far smaller than the number of viewers of her show.

The Power of Coincidence is strong, but it can lead us astray. The more we clearly understand the difference between clear connections and coincidences, the better off we’ll be.

This blog post is a rewrite of the one I did almost two years ago on a family initially suspecting vaccines of causing a case of Dravet Syndrome.


-Will FitzHugh

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Tags: Vaccine


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