There has always been opposition to childhood vaccinations. Ever since 1796 when Edward Jenner inoculated a young boy with a small amount of cowpox, a disease affecting cattle, as protection against smallpox, some parents have resisted vaccinating their children.

The opposition to vaccinations existed for two main reasons. First, the idea of injecting a small amount of an infectious disease agent into a healthy person to protect against the disease is counterintuitive, particularly if one does not understand how the body works. Second, mandating the vaccination of children can be perceived as government telling parents how to raise their children.

These two reasons could be considered somewhat legitimate until the mid-20th Century, before knowledge of the human body response to vaccinations and of epidemiology became widespread. Now it is known that vaccines stimulate the body’s own defenses against disease, and, it is known that vaccinating a large group of people offers more protection for each person in the group. The implications of this knowledge should be this: rather than mandated vaccinations killing or disabling children, they save children.

However, the anti-vaccination movement (anti-vax) received new life with the 1998 publication of a study connecting measles vaccinations to autism in the prestigious British medical journal, Lancet. The article was fully retracted by the journal in 2010, based on numerous published criticisms from the scientific community about the study’s shoddy methodology, and therefore the erroneous results. In the last two decades numerous studies with much better methodology have clearly demonstrated that there is no connection between measles vaccination and the onset of autism.

Unfortunately, it didn’t matter to some people; the 1998 article has taken on a life of its own. It is now the foundation document of the anti-vax conspiracy theory believed by many throughout the world. The belief is bad enough, but the behavior based on the belief is worse. Many parents not only refuse to have their children vaccinated against measles, they refuse to have their children vaccinated against anything! And of course the results of this are not surprising: measles has made a global comeback. The World Health Organization reports that 110,000 people died of measles in 2017, most of them children under 5 who had not been vaccinated against measles, the highest reported number in decades.

Like most believers in conspiracy theories, the anti-vax advocates have engaged in perceptual distortions. They hang onto the infamous 1998 article as gospel. They widely distrust institutions of all types; government, corporations, universities, the mainstream media, and scientific explanations in general. They give too much credence to their first impression, which is that measles vaccinations cause autism. They continue to hold this belief because they deny the validity of the refutations and the retraction. They justify their denial by claiming that the government, doctors and the pharmaceutical industry have a secret conspiracy to mandate vaccinations for one reason only- to make profit. They make this claim despite the fact that doctors make no money off of vaccinations, and the pharmaceutical industry historically made very little profit from vaccine production, and that the federal government and the industry are often in conflict about prescription drug policy.

Unfortunately the internet and social media have become a propagandizing force multiplier for this and all other conspiracy theories, increasing the number of believers. This sad story tells us at least two things about human psychology.

One, first impressions are extremely difficult to change. They can be maintained in spite of later overwhelming evidence to the contrary. Two, some people have a strong need to believe in mysterious malevolent forces that control our lives for some evil purpose.

In closing, the anti-vax conspiracy theory is not some cute anecdote for the amusement of conspiracy theory non-believers, like the belief that reptilian creatures secretly rule the world. The anti-vax conspiracy theory causes parents to not vaccinate their children, and the consequences of this are disastrous at both the individual and social levels. Therefore the rewards and punishments of a behavior modification program need to be applied to non-complying parents, for the sake of their own children and all other children.