Sunday, March 14, 2010

The Risk of Fear of Vaccines

I posted something on Facebook about the U.S. Vaccine Court denying claims of parents who said their kids’ autism was caused by vaccination. I suggested that the arguments over this supposed link are no longer really about the science of vaccines, which is far more settled than the science on, say, climate change.(The U.S. National Academies of Science meta analysis of dozens of studies is summarized at I suggested that the fears of those who still argue for the link are better understood by the science of risk perception, which helps us see that the fears are real, and must be respected, but they're not really about the facts regarding vaccines.

Several risk perception factors are at work here. Those who refuse to acknowledge the overwhelming evidence that there is no link between autism and vaccines don’t trust the government and pharmaceutical industry, and mistrust fuels fear. Parents with autistic kids have so little control over their children’s fate, and lack of control fuels fears. And any risk to kids evokes more fear than the same risk to adults. These risk perception factors are real, as real as the evidence disproving the autism-vaccines link. So despite a mountain of such evidence, the fears persist, and fuel a rising doubt about vaccines in general. I observed that this Perception Gap between the fear and the facts is dangerous, not only for parents who choose not to vaccinate their kids, but for everyone else, since herd immunity is important to keep largely defunct diseases like measles from spreading again.

I got two replies. One suggested that sometimes the cure – vaccination - is worse than the disease. Maybe in some rare cases, but not with measles, and other common diseases against which fewer people are being vaccinated. The danger of those illnesses is greater than the risks of the vaccines, which in rare instances cause allergic reactions, but according to worldwide scientific consensus do not cause the things the fearful parents claim. The body of evidence disproving the connection between autism and vaccines is as clear as one can possibly hope for in science, passionate doubters notwithstanding. One persuasive piece of evidence is the fact that thimerosal, the supposedly dangerous preservative in the MMR vaccines, was removed years ago under pressure from worried parents (despite no medical evidence that it posed a risk), yet the number of cases of childhood autism continues to rise.

Yet a few concerned people continue to doubt the safety of the Measles/Mumps/Rubella (MMR) vaccine, and their passion has spread to a rising fear of all vaccines. 54% of American parents worry about vaccines having serious side effects on their kids, and one parent in eight has refused at least one vaccine their pediatrician has suggested. (The University of Michigan study is summarized at Herd immunity to measles has dropped so low in some places that measles cases are rising dramatically, and in a few tragic instances it's killing children again. In 2008 the U.S. had more measles cases than any year since 1996. (It’s even worse in the U.K., Germany, Switzerland and Israel, among other countries.)

There is another risk perception factor at work here too. Risk v. Benefit. Not long ago when measles and other childhood diseases were widespread, and lethal in hundreds of cases, the benefit of the vaccines outweighed their risk. Now the risk of the diseases has become so low that we only worry about the drugs. Curious. Because they’ve succeeded, we worry more about the vaccines than the diseases from which they are protecting our children.

The other note I got, from a thoughtful friend and father of an autistic child, was rife with mistrust of scientific findings that disagree with his beliefs. He focuses his mistrust on only one or two studies denying the vaccines-autism link, about which conflict of interest questions have been raised, but ignores hundreds more that find the same thing. He mistrusts government and pharmaceutical companies. As we all should, to a reasonable degree. This thoughtful friend says that if the science is that strong, it will stand up to scrutiny. It has, many times over, at least to those not seeing the issue through the perspectives of their fears. When is there enough evidence? Only when it agrees with what we want it to say? When is there enough evidence so that we don't automatically dismiss as untrustworthy anyone who provides an answer which conflicts with our fears?

This isn't about denigrating the real and passionate concerns of those whose fears don't match the mountain of evidence that says they're wrong. Trust matters. Control matters. Risks to kids will always evoke deep concerns. It makes sense that we're less worried about diseases that are mostly forgotten so the benefit side of vaccines is less obvious than the risk side of the tradeoff. In the context of risk perception psychology, these fears make sense.

Rather, this is about making healthy choices. Not just for our own children, but for our friends and neighbors and society at large as well. Decision making from the heart, no matter how right those passions feel, may lead us into greater danger. We need to find out what is causing the rise in autism. Focusing on the disproved link with vaccines diverts time and attention from potentially more telling lines of investigation. It fuels a growing public mistrust in science and government. Sometimes our worries, as valid as they are, can get so unreasonable that the Perception Gap becomes the greatest risk of all.

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