I’ve been involved in several boisterous Twitter debates about vaccines, at least to the extent that one can debate using snippets of 140 characters or less. I’ve also been a “super moderator” at a very large Internet message board for many years and have seen my share of passionate vaccine debates there. I’ve been a pediatrician for over 30 years and trained in the subspecialty of pediatric infectious diseases before I went into critical care.

So I think a lot about vaccines and have watched controversies about them come and go for a very long time. It’s been interesting. One very interesting aspect for me is trying to understand how parents think about the relative risk of medical treatments and procedures for their children. It’s different from how physicians think of risk, and I think this difference is key to understanding the continuing ferment over vaccinations. I’ve previously written about the risk of a vaccine injury (about 1 in a million at worst) compared to the risks of everyday life, but there is another aspect to the issue: in my experience parents are uniquely worried about vaccine risk in ways they are not about other medical procedures and treatments. A few examples illustrate my point.

Stevens-Johnson syndrome is a severe skin reaction to something, most commonly a medication. It varies in severity but can progress to a very bad condition known as toxic epidermal necrolysis. This is a life-threatening condition and often requires a prolonged stay in the intensive care unit. I have seen several life-threatening cases over the years. The drugs that can cause it are quite common ones. Many are antibiotics: Sulfa drugs, for example, are well-known offenders. How common is this condition? There are about 300 cases per year in the USA. This makes it much more common than vaccine injury, yet nearly all parents think of antibiotics as safe drugs. On balance, they are — but they are not risk free.

Medications like antibiotics can cause other kinds of allergic reactions, which can be severe or life-threatening. A very conservative estimate is that about 0.01-0.05 % of all people — about 1-5 per 10,000 individuals — will have such a serious drug reaction in their lifetime. Yet parents accept prescriptions without worrying about that.

Another example is anesthesia. As part of my practice I anesthetize many children for procedures, such as MRI scans. The risk of doing this is low, but it is well above zero. The actual risk of death from an anesthetic is around 1 in 250-300,000 — about 3 times the risk of a serious vaccine reaction. There also may be neuro-developmental risks to young children who receive anesthetics. That risk is very low, too (there are many studies ongoing to define it), but it is not zero. Of course if a child needs emergency surgery the balance of risk versus benefit overwhelmingly favors using the anesthetic, but there are many other situations that are not so clear-cut. Yet virtually all parents willingly allow me anesthetize their child.

My point is that vaccine risk, compared with the risks of other medical interventions, causes particular concern among parents, and I am not sure why that is. However, it is not new. Since the introduction of the very first vaccine, Edward Jenner’s use of smallpox vaccine, people have been particularly suspicious of vaccines. (The name “vaccine” itself is derived from Jenner’s use of the vaccinia virus, the cowpox virus, as a protection against smallpox.) As noted in the essay linked above:

Although the time periods have changed, the emotions and deep-rooted beliefs—whether philosophical, political, or spiritual — that underlie vaccine opposition have remained relatively consistent since Edward Jenner introduced vaccination.

I suppose the notion of putting a foreign substance into a child’s body with the intention of provoking the body to react to it is philosophically distinct from giving a child a medication that is not intended to do that. But I would be very interested in what other people think makes vaccines unique.

Christopher Johnson is a pediatric intensive care physician and author of Keeping Your Kids Out of the Emergency Room: A Guide to Childhood Injuries and Illnesses, Your Critically Ill Child: Life and Death Choices Parents Must Face, How to Talk to Your Child’s Doctor: A Handbook for Parents, and How Your Child Heals: An Inside Look At Common Childhood Ailments.  He blogs at his self-titled site, Christopher Johnson, MD.