Innumeracy and the cult of anti-vax

The last post was about an innate understanding of scale and scope, and how this lead to a general understanding of magnitudes.

A real world example, and one that is top of the news lately is the whole “anti-vaccine” movement. This is the increasing tendency to choose to not vaccinate your children due to the faulty belief that vaccines are worse than the disease. Leaving that argument aside, lets apply this “scale” thing to the antivaccine argument:

Measles, a once common childhood disease, has several bad results, with the death rate being on the order of 3 per 1,000 infections. (I will admit that I am horrified by how high this is.) That means that if 1000 children contract the measles virus, 3 will die. Let that sink in. That is a 0.3% fatality rate. Seems pretty low, until …

The MMR (Measles, Mumps, and Rubella) vaccine has pretty much eradicated the disease. In 2000 there were virtually no cases reported in the USA.

Of course, the vaccine is not risk free. The major risk is an allergic reaction to an ingredient, usually the albumin (protein from the white of an egg), causing an anaphylactic reaction. This is somewhat on the order of less than one event per million doses. That is almost three orders of magnitude lower than the risk of death. (1/1000 the risk). And guess what, when you get a vaccine, the healthcare provider has an epi pen ready for the vanishingly rare anaphylaxis, so even if you do have such a reaction, you will get immediate treatment for it. There is also a more common reaction, of a fever, a rash, and other symptoms, all of which are far less risky than the disease. None of these are considered life threatening.

So, the risk of a vaccine adverse reaction is 1/1000th the risk of DYING from the disease itself.

The truly horrifying statistic is the rate of death in immunocompromised victims of measles. That mortality rate is a staggering 30%. That means that if your child is immunocompromised, and contracts the disease, they have a nearly 1 in 3 chance of dying.


The general population is poorly prepared to weigh risks, and scale. Clearly, the benefits of vaccinating your children vastly outweighs the risks with vaccination, but the specious arguments bantered about highlight how little
the general populace understands the scope and scale of the risks.

Leave a Comment