The anti-vaccine movement: Is it too late for scientists to bridge the gap between evidence and fear?

Hot on the heels of yesterday’s paper in Pediatrics showing that vaccine refusal elevates the risk of pertussis in a child by nearly 23-fold, a commentary in PLoS Biology asks what can be done to combat anti-vaccine misinformation. Entitled A Broken Trust: Lessons from the Vaccine-Autism Wars, it’s an interview with a professor of medical anthropology at UCSF named Sharon Kaufman, who took a 26 month hiatus from her usual work on aging and longevity to study the anti-vaccine movement from an anthropological perspective. Her observations in some way echo observations I’ve been making as a commentator and blogger, but she also makes at least one suggestion that strikes me as rather implausible, if not wildly so.

The article treads on ground that I’ve covered many times on this blog before in that it gives a good, concise history of the latest incarnation of the anti-vaccine movement since the late 1990s, when a confluence of two events, one in the U.K. and one in the U.S., worked to plant the seeds of antivaccine lunacy that continue to germinate now, over a decade later. The U.K. incident was, of course, the publication of the infamous Lancet paper by scientific fraudster Andrew Wakefield, who was also in the pocket of trial lawyers who were suing vaccine manufacturers. That was 1998. The second, which occurred in the U.S. in 1999, was the sudden decision, bulldozed through merican Academy of Pediatrics’ vaccine advisory committee and the CDC mostly due to Dr. Neal Halsey, to recommend the removal of mercury from all childhood vaccines by the end of 2001. As described in the PLoS Biology article:

Given the uncertainty about ethylmercury’s toxicity, Neal Halsey, director of the InstituteIn 1997, a US congressman from New Jersey inserted into a funding bill a provision that gave the Food and Drug Administration (FDA) two years to measure levels of mercury in all products under its jurisdiction, and release its findings to Congress and the public. The FDA’s analysis revealed that because several new vaccines were added to the immunization schedule after 1988, some infants could be exposed to as much as 187.5 micrograms of ethylmercury by the time they were 6 months old–if every dose of Hib, hepatitis B, and DTaP contained thimerosal [11].


Given the uncertainty about ethylmercury’s toxicity, Neal Halsey, director of the Institute for Vaccine Safety at Johns Hopkins University, urged vaccine policymakers at the CDC and American Academy of Pediatrics (AAP) to remove thimerosal from vaccines as a precautionary measure and to maintain public confidence in their safety. The agencies agreed, and vaccine manufacturers responded quickly; by March 2001, no children’s vaccines contained thimerosal.

Anticipating the FDA’s release of its findings, the AAP issued a statement explaining its decision as an effort to minimize children’s exposure to mercury, asserting that “current levels of thimerosal will not hurt children, but reducing those levels will make safe vaccines even safer” [12]. Unfortunately, Kaufman says, “rather than reassuring parents, the statement fueled public fears and prompted all sorts of questions.”

To this day, this is one of the most spectacular examples of the law of unintended consequences that I’ve ever seen, and I can’t believe that anyone would think that a line like “the current levels of thimerosal will not hurt children, but reducing those levels will make safe vaccines even safer” would do anything other than what it did: spark a panic. Talk about your classic case of mixed messages! On the one hand, the government was saying that thimerosal was safe, but on the other hand it was removing thimerosal from vaccines. The discordant messages fed the worst aspects of the conspiracy-minded (and if there’s anyone who’s conspiracy-minded, it’s members of the anti-vaccine movement). One observation in the article intrigued me:

Had the discovery about thimerosal come at a different time, it might have gone unnoticed, suggests Jeffrey Baker, a pediatrician and the director of the Program in the History of Medicine at Duke University. He argues that rising autism rates, an expanded vaccine schedule, and contemporary attitudes toward environmental risk combined to create what he terms “a perfect storm” [15].

Certainly, it’s an interesting concept, but I’m not sure that it’s a good explanation, for the simple reason that the U.K. antivaccinationists had already shown the way, latching on to Andrew Wakefield’s horrifically bad science to confuse correlation with causation and blame the MMR for autism. The myth of the “autism epidemic” had already begun. All parents who were already suspicious of vaccines needed was something to blame, and a conspiracy theory was born. Unfortunately it’s still going strong, fueled by a toxic brew of pseudoscience, quackery, and celebrity know-nothings like Jenny McCarthy and Jim Carrey dancing on their strings according to the will of their puppetmasters in the antivaccine movement. But the real question is why? Why is this myth so resistant to science, data, and reason?

Here’s one possibility:

Kaufman thinks the problem is more immediate than bridging the gap between lay and expert understanding of risk. Parents treated theoretical risk as fact even as scientists tested, and ultimately rejected, the possibility that thimerosal might harm children. Thinking the institutions that were supposed to protect them from risk failed, Kaufman says, people now do their own research. But instead of leading to more certainty, she explains, “collecting more information actually increases doubt.”

With the explosion of “contrary” expertise online, Kaufman says, “many parents see even the most respected vaccine experts’ perspective on the issue as just one more opinion.” The bulk of antivaccination Web sites present themselves as legitimate sources of scientific information, using pseudoscientific claims and emotional appeals, according to a 2002 study in Archives of Disease in Childhood [19]. Making matters worse, the study found, nearly all sites adopted an “us versus them” approach, casting doctors and scientists as either “willing conspirators cashing in on the vaccine ‘fraud’ or pawns of a shadowy vaccine combine.” Parents’ intuitive views about vaccines were elevated above “cold, analytical science.” Accounts of children “maimed or killed by vaccines” were common–a finding that may help explain why those who advocate immunization receive death threats.

I’ve touched on this before many times. One problem is that vaccines have been so successful that parents rarely see the full, ugly consequences of the diseases against which vaccines defend anymore. The other problem is that normal people can’t adequately judge risk. They cannot understand that they do many, many things with their children that pose far more risk to them than vaccination ever could for a lesser benefit. For example, the risk of dying in an auto collision is several orders of magnitude higher than of a serious adverse event from a vaccine. The risk of death from playing baseball (hardball) is also several orders of magnitude higher than injury from a vaccine. Indeed, as I pointed out before, between four and five children per year die of injuries suffered while playing baseball, and well over 100,000 children a year are taken to the emergency room for injuries. Indeed, baseball has the highest child fatality rate of any sport, and there are nearly 3 million sports injuries a year in the U.S. So what do antivaccinationists fear more? Vaccines, of course! Why? Because they misunderstand science and expect scientists to prove that vaccines don’t cause autism. Unfortunately, conclusively proving a negative is not possible in science. We can assign probability based on data, and numerous studies tell us that the chances that vaccines contribute significantly to autism is vanishingly small, but non-scientists think that it’s possible to prove that vaccines don’t cause autism and become suspicious when scientists qualify their statements. What to scientists is normal caution comes across to the public as waffling or weaseling.

Another aspect that gives the antivaccine movement the edge, even more so than other anti-science denialist groups, is the power of the story. They routinely present such compelling testimonials of children regressing after a vaccine. It doesn’t matter that epidemiology has shown repeatedly that correlation does not equal causation; the story is what matters because we are storytelling animals. As Paul Offit put it:

“There’s a lot of good autism research out there,” says Paul Offit, chief of infectious diseases at Children’s Hospital of Philadelphia and head of the hospital’s Vaccine Education Center. . . “But you never hear about it because the anti-vaccine movement has taken this issue hostage.” Offit has turned down requests to appear on any show with McCarthy. “Every story has a hero, victim, and villain,” he explains. “McCarthy is the hero, her child is the victim–and that leaves one role for you.”

Or any scientist who faces women like McCarthy. It’s almost a no-win situation. The question is: Is there any way to overcome the power of the anti-vaccine “regression” story, which is often subject to confirmation bias or lack of knowledge of what to look for that leads parents to discount abnormal or “strange” behavior before vaccination that experts, when viewing videotapes, can immediately recognize as early autism symptoms. That’s exactly what happened in the Michelle Cedillo test case for the Autism Omnibus. Her parents submitted videotapes to the court as evidence that Michelle was “perfectly normal” before she received her MMR vaccine. Experts who looked at these videotapes saw clear signs of autism. The problem isn’t just the story; it’s the story that doesn’t mean what parents think it means. It’s the misremembered story that becomes infused with myth and groupthink. Compared to that, what is suggested seems tame indeed:

McCarthy emerged as a hero for some parents by telling her story. Personal stories resonate most with those who see trust in experts as a risk in itself–a possibility whenever people must grapple with science-based decisions that affect them, whether they’re asked to make sacrifices to help curb global warming or vaccinate their kids for public health. Researchers might consider taking a page out of the hero’s handbook by embracing the power of stories–that is, adding a bit of drama–to show that even though scientists can’t say just what causes autism or how to prevent it, the evidence tells us not to blame vaccines. As news of epidemics spreads along with newly unfettered infectious diseases, those clinging to doubt about vaccines may come to realize that several potentially deadly diseases are just a plane ride, or playground, away–and that vaccines really do save lives.

The problem, of course, is that it’s very hard to come up with stories that don’t somehow distort the science. I also don’t like the attitude behind this article that regular people can’t understand science. What this simplistic narrative as told by Liza Gross is missing something huge: Scientists did try to counter the antivaccine movement. They are trying to counter it now. They’ve tried every step of the way. It is true that they may have waited too long. I’ve frequently lamented that efforts to counter the antivaccine movement were few and haphazard until last year, when scientists and authorities seemed finally to wake up to the danger. The damage had been done, and anti-vaccine zealots had infiltrated the national zeitgeist to such an extent that parents were starting to believe the lies (or at least wonder if they were true or whether authorities were telling the whole story). I do not in any way mean to trivialize such tragedies, but few stories of parents with children who suffered complications from vaccine-preventable diseases will not change things. Just look at the comments I pointed out yesterday, specifically the mother who did trivialize the suffering of her children with pertussis, who were severely ill for a week with horrible coughing and continued to cough for ten weeks. She dismissed their suffering as “not real serious.”

It is possible that coming up with more compelling stories may make a difference, but if it does it won’t be among the hard core anti-vaccine believers. Antivaccine activists don’t care; they’ve drunk so deeply of the Kool Aid. They believe. They believe so much that often they will invest huge sums of money into quackery designed to reverse “vaccine injury.” Against that, I have a hard time envisioning how counter-stories could combat the narrative of the anti-vaccine movement without risking serious distortions. I would, of course, like to be shown to be wrong about that–as wrong a the anti-vaccine movement is about vaccines. I wouldn’t mind it at all. But I’d settle for swaying the undecided.


Gross, L. (2009). A Broken Trust: Lessons from the Vaccine-Autism Wars PLoS Biology, 7 (5) DOI: 10.1371/journal.pbio.1000114