Vaccination Policy and the Igon Value Problem

    One of the unmistakable patterns in the public forum debates on vaccination safety and vaccination policy is that the trained health care professionals tend to line up on one side, while the most engaged public voices end up on the other. One way to interpret this divide is through the lens of conspiracy theory – that those of us in medicine have an indoctrination, and can’t think critically about the current policy. So, groups of self-appointed non-scientist activists have to step in to correct our errors.

    Another way to interpret the varying opinions by level of expertise is that people who study a field learn things that others don’t.  Medical training (at least in the best case scenario) comes with a heavy dose of science instruction. By the time a young doctor graduates from school, he or she should be fairly conversant with pharmacology, toxicology, chemistry, and biostatistics. Each of these comes in handy as we interpret and act upon the almost staggeringly large body of evidence that supports our current vaccination policy.

    Which brings me to the Igon Value Problem. This term was first proposed in Steven Pinker’s review of Malcolm Gladwell’s book “What the Dog Saw.” In the book, Gladwell misquotes a mathematician regarding the math term eigenvalue, reporting it instead as igon value. To the casual reader, this likely passed unnoticed. To experts in math, however, this was likely to be either irritating or laugh-out-loud funny.

    This is the classic dilettante problem. People who try to read and interpret medical research without training or understanding are not going to be able to contextualize the findings in a way that is consistent with the current understanding in the field. As such, they will make errors that seem obvious and/or intentional to people who have real training. If you add on top of this a bias against the medical establishment so common in the anti-vaccine community, you’ll see a predictable pattern emerge. You’ll often see the usual voices both overstate the risk and cast doubt on the preventive benefit of our current vaccines.

    For example, here’s a recent article from discussing vaccine risk. It makes the claim that no prospective research exists comparing vaccinated and unvaccinated populations. An expert in the field would know two things. One, they would know that some observational trials exist (summarized well here).Two, that no study like that could or would ever be approved through an institutional review board because it would be considered unethical to expose a group of children to unnecessary disease risk.

    In the same article, we see the zombie myth that vaccines cause autism presented as fact. An expert would know that a meta-analysis published two years prior analyzed data on more than one million children and showed that there was not even the slightest hint of a link. The expert would feel obligated to at least mention this fact, and explain why the conclusion was not valid. The dilettante can just whistle and walk on by.

    We often see popular anti-vaccine blogs complain about the density of the current CDC vaccination schedule. Often, they talk about the number of protective vaccinations with the unexplained and unchallenged assumption that it would be bad or scary to have more. In contrast, scientist generally do not express any concern about the number of vaccines nor about schedule density because they understand the body of evidence that these schedules are built around. For example, the 2013 Institute of Medicine safety review would likely be sufficient to satisfy most all people with medical training that our vaccination schedule is based in sound science and careful monitoring.

    A frequent topic in the non-science anti-vaccine blogosphere is the use of potentially toxic adjuvants in vaccines. For example, many articles note that vaccinations may include formaldehyde to attenuate live viruses. It is true that formaldehyde exposure can be harmful. But someone familiar with toxicology would take the time to assess the dose, and compare it to amounts known to associate with risk. If our blogger friends would have done this, they would have learned that the entire pediatric schedule contains less formaldehyde than a medium sized apple, and we don’t generally think of apples as an existential threat. Oh, and an expert might also know or learn that the half-life of formaldehyde in the blood is less than two minutes. Vaccination formaldehyde is basically cleared from circulation by the time the child gets back out to the waiting room.

    In medical journals, doctors debate difficult topics in great detail. Often using tools from statistics or study design assessment to help determine which of two competing hypotheses have the most merit. For example, I’ve recently been following debates about the value of restriction of dietary salt in people with heart failure and about how much of a risk factor diets high in saturated fat are for coronary artery disease.

    We do not find parallel debates in the vaccination literature. The fact is, the risk to benefit ratio of the current vaccines in the current schedule is well documented, and the evidence is out there in the public domain for those who care to take the time to go find it. There is no current debate among experts about the need for fewer vaccines (except, perhaps, as it relates to policy and uptake). There is no current debate about the safety and wisdom of using vaccines in neonates. These things were assessed a long time ago, and are currently considered settled science. People who study medicine, nursing, vaccine development, and public health learn why in the first years of their training.

    I realize that this may be the single worst time in history to suggest that people should “trust the experts.” It seems that faith in our institutions, including medicine, erode by the day. But the argument I am making here is not that we should follow expertise wherever it may lead. Instead, I am cautioning the most vocal vaccination critics that their lack of scientific training blinds them to how flawed their arguments nearly always are.

    One of the many wonderful things about science is that it is an egalitarian community. Science doesn’t care whether you are for or against universal vaccination policy, whether you are on the side of the CDC or the personal injury lawyers, or whether you trained at Harvard or your local community college. I challenge any of our prominent and public vaccine critics, if they want to be taken seriously, to obtain real science training, and devote their career to testing the safety of vaccinations. Lacking this, however, I hope they will learn to be a little more humble about their public pronouncements.

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