On the Stubborn Persistence, and the True Underlying Causes, of Vax-O-Noia

As attention fades from the Disneyland measles outbreak and the hue and cry about parents who don't vaccinate their kids dies down, it will be interesting to see how much impact this outbreak will have on vaccination rates. If previous episodes are any guide, a safe prediction is very little.

There will be some change, of course, at least in some areas, for a little while. More states will join the few that had already begun making it harder for parents to opt out of mandatory school vaccination requirements for their kids. (California is proposing eliminating parental choice altogether.) For a time it will be politically easier for governments to change the rules and limit personal choice.

The social stigmatization of the few parents who don't vaccinate their kids at all (accounting for fewer than 1 percent of American children), and of the wider group of parents who pick and choose which vaccines their kids get and when, rather than follow the medically tested and recommended schedule (accounting for up to 6 to 7 percent of American children), will persist. Sadly, the un- or undervaccinated children will be treated like little lepers too.

And certainly the unusually high visibility that this outbreak received in the media (due to the Disneyland effect) has made it clear that measles is not gone, which is already encouraging some vaccine-hesitant parents choose them anyway.

But these are relatively small-scale changes, and given what we've seen after much-larger outbreaks over the past few decades in many U.S. cities and other countries, they are likely to be temporary. The problem of vaccine hesitancy is persistent and deep. A few weeks of media attention are unlikely to change the basic causes of Vax-o-Noia, a clarion example of the risk-perception gap -- when we fear some things too much (the vaccines) and some things too little (the diseases) -- and those perceptions create risks all by themselves.

The underlying risk-perception psychology that explains vaccine hesitancy has been evident ever since Edward Jenner smeared cowpox on 9-year-old James Phipps in 1796. Jenner was ostracized from his community, a huge anti-vaccine movement sprang up, and the battle against vaccination has been raging ever since, waged based on themes similar to those we hear today. (Here's an interesting look at what vaccine deniers were saying 100 years ago. It will sound familiar.)

What this tells us is that we have to look far deeper than just Andrew Wakefield's claims in the late 1990s that vaccines cause autism for a real explanation of Vax-O-Noia. Wakefield was only the trigger of this most recent version of a long-standing fear. And we have to go beyond surveys like the one recently done by the Pew Research Center, which found that millenials seem to worry more about vaccines than people in other age groups. Such surveys reveal only the surface demographics, not the underlying psychology that is really driving this instinctive and persistent concern.

We can find the deeper explanations of Vax-O-Noia in the research on risk perception by Paul Slovic and others, which has identified innate psychological characteristics that makes some risks scarier and some risks less scary.

1. We worry more about risks that we feel uncertain about, like potential threats we can't detect with our own senses, or possible dangers that are scientifically difficult to understand. Uncertainty means we don't feel like we know what we need to know to protect ourselves, powerless, which fuels our fears.

2. We worry more about risks that are human-made than risks that are natural. (Even Jenner's vial full of natural cowpox pus was injected into young James by humans, not "naturally.")

3. We worry more about risks that are imposed on us than about risks we choose to engage in voluntarily.

4. We worry more about risks that are generated by sources -- people, governments, companies -- that we don't trust.

5. We worry more about risks to kids than about risks to adults.

6. We worry more about risks that are getting a lot of attention, the kind of attention the risk of vaccines got from the media only recently.

7. We worry more about even small risks -- vaccines do have rare and almost always minor side effects -- if they provide little or no benefit, which feels like the case when vaccines work and all but eliminate certain diseases.

Across the entire history of Vax-O-Noia, you can see some or all of these basic psychological characteristics behind the public's fears. Each outbreak may have had its own unique circumstances, but they were all responses to at least some of these underlying risk-perception alarms. And if this is where the true causes of vaccine concern lie, it is where we have to look for solutions.

The psychology of risk perception can help us design communication and education that can demonstrate an understanding of and respect for people's feelings, which can build trust and increase influence on some people's choices. Understanding the psychology of vaccine hesitancy can help us craft policies that encourage people to vaccinate (economic incentives through insurance programs, like we do for healthy behaviors like not smoking or maintaining an accident-free driving record) or discourage them from avoiding vaccination (economic disincentives on insurance, making it harder to opt out, or limiting the participation in school or social activities by those who aren't vaccinated and pose a risk to others) when communication doesn't work.

So hopefully one of the outcomes of this recent Disneyland measles outbreak will be more research to confirm the underlying psychological drivers of Vax-O-Noia. Unless we understand the root cause of this persistent threat to public health and apply that understanding to the task of addressing people's fears, episodes like the current outbreak will continue to occur and piecemeal temporary responses will follow, but the public will remain at risk from diseases that vaccines can control.