Time for Society to Say Enough is Enough.  

       The science community laments that people deny the evidence science produces. Usually this complaint is merely descriptive, intellectual frustration sometimes tinged with arrogance. Sometimes the criticism of denialism also offers solutions, which usually include education and communication to make the deniers stop denying, to make them see things the rational way the science community thinks everyone can, and should. Rarely does the conversation get to the uncomfortable final prescriptive answer of what we should do when the intrinsic nature of risk perception causes people to steadfastly deny the evidence, no matter how well-informed and educated they may be, and their behavior puts other people at risk. There is no better example than vaccines.

       For a number of reasons, well-explained by research into the psychology of risk perception, the fear of vaccines has become so entrenched that no amount of communication or dialogue or reason will get some of the people worried about vaccines to stop worrying. These fears are clearly creating danger for the greater community. Usually when people’s perceptions of a risk produce behaviors that harm others…we make them stop. We pass laws or impose economic rules, or find other ways to discourage individual behaviors that threaten the greater common good. We do this all the time. You don’t get to drive drunk. You don’t get to smoke in public places. You don't even get to leave your house if you catch some particularly infectious disease.

       Then what should we do about people who decline vaccination for themselves or their children, and put the greater public at risk by fueling the resurgence of nearly eradicated diseases? Isn’t this the same thing, one person’s perception of risk producing behaviors that put others at risk? Of course it is. Isn’t it time for society to say that in the greater public interest, we need to regulate the risk created by the fear of vaccines? Yes. It is.

       First, a few facts about the harm caused by the fear of vaccines.

- The European Center For Disease Control reports outbreaks of measles in many countries where vaccination rates have gone down: As of June - France (12,699 cases in 2011, more than in all of 2010 already, including six deaths), Spain (2,261), Italy (1,500), Germany (1,193, one death). There have already been 550 measles cases in England and Wales this year compared with 33 all of last year.

- The U.S. has had 156 cases as of mid-June, compared to a total of 56 cases per year from 2001-2008. The CDC has an emergency health advisory for measles, a disease officially declared eradicated in the United States in 2000.

- A 2008 study in Michigan found that areas with "exemption clusters" of parents who didn’t vaccinate their kids were three times more likely to have outbreaks of whooping cough than where vaccination rates matched the state average. In 2010 as California suffered its worst whooping cough outbreak in more than 60 years (more than 9,000 cases, 10 infant deaths), Marin County, one of the richest and most educated areas in California, had one of the lowest rates of vaccination statewide and the second highest rate of whooping cough.

- The risk is not just to people who have opted out of vaccination. Of the 156 measles victims in the U.S. as of June, nearly one in five of them had been vaccinated but the vaccine didn’t work, or had weakened. Infants too young to be vaccinated are getting sick, and some of them are dying, when exposed to diseases where ‘herd immunity’ has fallen too low to keep the spread of the disease in check. Unvaccinated disease victims cost the health care system millions of dollars, and local and state government millions more as they try to bring each outbreak under control. A recent economic analysis found that "…vaccination of each U.S. birth cohort with the current childhood immunization schedule prevents approximately 42,000 deaths and 20 million cases of disease, with net savings of nearly $14 billion in direct costs and $69 billion in total societal costs."

       Elsewhere (The Los Angeles Times, BigThink.com) I have laid out a more detailed case for what society might want to consider about how to regulate the behavior of people who decline to vaccinate themselves or their children and put the greater community at risk (make it harder to opt out of vaccinations, encourage vaccination with discounts on the cost of health insurance or penalties for those who opt out, restrict the social/community facilities unvaccinated people can use or activities in which they can participate). Here I’d like to describe some of the underlying psychology that helps explain why the fear of vaccines exists, and why it is so strong, and why no amount of communication or discussion or reason will get people deeply worried about vaccines to stop worrying. Which is why society has to step in and act.

       Risk perception is a largely subconscious subjective interpretation of the facts, as seen through powerful emotional/instinctive filters that we have evolved to help us quickly gauge whether something is dangerous: 

- Children. Any risk to kids worries us more than the same risk to adults.

- Control. Powerless against a risk makes it seem worse. It is entirely understandable that any parent of an autistic child wants answers, and hope, and a sense of control, over the fate they’ve been cruelly dealt.

- Human-made v. Natural. Human-made risks, like pharmaceutical vaccines, evoke more fear than natural ones.

- Risk versus Benefit. It is understandable for a parent to decline vaccinations they fear might be a greater risk to their kids (even if the risk is low) than the diseases the vaccines have largely (but not entirely) eliminated.

- Imposed or Voluntary. A risk imposed on us worries us more than if we engage in it voluntarily, so it’s understandable that people are troubled by state-mandated vaccination (though the individual liberty argument rings hollow against the fact that in 21 states people can opt out of having their kids vaccinated for “philosophical reasons”, and in 48 states for religious reasons – without any proof that their faith actually bans vaccination).

- Trust. We fear risks from institutions we don’t trust, like the pharmaceutical industry, and government, and even, for some of us, big business generally.

- Cultural Cognition. Some people feel that that society should be more fair and flexible than it is and that people should not be constrained by rigid social or economic class hierarchies. These people, known in the study of Cultural Cognition as Egalitarians, criticize the major institutions of the modern economy – big corporations (and their products) – which Egalitarians blame for contributing to unfair and restrictive class structures. (Egalitarians are commonly politically liberal, like the population in Marin County.)

Mistrust, lack of control, human-made risks imposed on our kids, risks that seem to outweigh the benefits,…given these powerful instincts, the fear of vaccines is understandable, even if it flies in the face of overwhelming evidence. As irrational as those fears seem to the science community, it is also irrational for that community and policy makers to ignore the overwhelming evidence that risk perception is a subjective mix of facts and how those facts feel. It's irrational for these ‘rationalists’ to continue to expect that an evidence-based argument alone will change vaccine opponents’ minds.

So it is time for us to act, and regulate the behavior of those who refuse to vaccinate themselves or their children. But the vaccines issue teaches a larger lesson. The affective/subjective/emotional perception of risk comes from such deep survival instincts that it sometimes can not be closed with communication and reason, and while these instincts often protects us well, they sometimes produces a Perception Gap which can be a risk all by itself.

Rather than struggle against this intrinsic facet of human nature by calling it science denialism and irrationality, a more holistic approach would accept that sometimes we get risk wrong in dangerous ways. This approach would allow us to account for and manage the dangers of the Perception Gap with the same tools we already use to manage myriad other threats. And in the case of vaccines, it should mean that we do what we always do when one person’s behavior threatens the greater community. We make them stop.  

About the Author: David Ropeik is an Instructor at the Harvard Extension School and author of   How Risky Is It, Really? Why Our Fears Don't Always Match the Facts .

The views expressed are those of the author and are not necessarily those of Scientific American.

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