Two Key Distinctions for Understanding the Value of Vaccinations

Feb 18, 2015

IPFW Associate Professor and medical ethicist Abraham Schwab.
Credit Courtesy / Abraham Schwab

It’s a surprising thing that Mississippi and West Virginia are the two states with the highest vaccination rates. Less surprising: this fact is attributed to a simple policy—these states do not allow religious or personal exemptions from the policies requiring vaccinations.

These policies put public health ahead of unbridled individual liberty. Chris Christie has not openly criticized these states, but he voiced a belief that the parents should have some say in the decision to vaccinate. Whether you agree more with Christie or more with the state of Mississippi, two key distinctions warrant our attention before we make either a personal or a policy judgment about vaccinations.

Stories vs. Science

Science and opinion are not the same thing. For example, after watching this scene, you might be convinced that objects fall to the earth at different rates of acceleration. And, despite the richness of the example, you would be wrong. You’re entitled to that opinion, of course, but we shouldn’t base any policies on it and we shouldn’t put others at risk because of it.

There's a robust difference between a story and science.

A story is noticing a few things happening around the same time. Science is understanding how these things happened and reliably predicting they will happen this way again.

Personal stories can be quite compelling, while the numbers, formulas, and algorithms of science can be quite dull. Put several similar stories together and you might get an attention grabbing, provocative correlation (when ‘this’ happens, then ‘that’ happens). It’s not surprising then that collections of stories implying certain correlations have been used by the media and politicians like Michele Bachman and Rand Paul to justify certain views about vaccines.

There’s a substantial risk to setting policy according to the correlations--correlations are notoriously easy to produce. For example, if we set policy according to a good correlation, we should move to outlaw the sale of organic foods. As this graph demonstrates, there’s a correlation between organic food sales and the rise in autism diagnoses. 

This image is easy to grasp, visually stimulating, and more entertaining than an article debunking the causal link between autism and vaccines. And yet, we should set policy according to the rigors of science rather than the ridiculous possibilities of correlations. A robust and reliable conclusion should be preferred to the provocations of a good set of stories.

There’s Mercury and Then There’s Mercury

As someone who’s been working on losing weight and improving my fitness, I recently realized the multifaceted value of tuna. It’s high in protein, low in calories, and with a little Sriracha sauce, has a good flavor. The downside of tuna—methylmercury.

Methylmercury, usually referred to as simply ‘mercury’, builds up in the meat of the tuna and so when we eat tuna, the methylmercury gets into our system. And it doesn’t get out. Methylmercury builds up in our system and too much of it can have both short term and long term effects. And so we’ve come to view (methyl)mercury as something we should treat with caution and avoid when possible.

It turns out there’s an ingredient (thiomersal) used to preserve bottles of vaccines that contains mercury. Given our concerns about (methyl)mercury, this seems concerning.

But -- and this is the key point -- the substance used to preserve vaccinations (thiormersal) contains ethylmercury. Unlike methylmercury, ethylmercury is broken down by our bodies much faster and finally leaves the body.

The pay-off: concerns about thiomersal and mercury in vaccinations are the result of a homonymy and subsequent equivocation. One word refers to two different things, which can trick us into a false conclusion. The (ethyl)mercury in vaccines does not carry the risks of the (methyl)mercury in fish (and other foods) because it is not the same type of mercury.

As we continue our conversation about the best way to handle measles, mumps, rubella, smallpox, polio, and the lowly flu, keep in mind that a good story may be only a story and that not all mercury is the same.

[One note: this article does not specifically take on the fabricated claim that the Measles Mumps and Rubella (MMR) vaccination includes a risk of causing autism. This claim has been as clearly refuted by the scientific literature as a claim can be. If you’re looking for a broad overview of this false claim and its implications, this Wikipedia entry provides a nice overview with lots of links to external sources.]

 

Abraham Schwab is an associate professor of philosophy and a medical ethicist at IPFW.

Opinions expressed in this column are those of the individual writer and do not necessarily reflect the opinions of the staff, management or board of Northeast Indiana Public Radio. If you want to join the conversation, head over to our Facebook page and comment on the post featuring this column.