Vaccine Studies and Conspiracy Thinking

February 13, 2010 in Medical Ethics by RangelMD

Conspiracy theorists (i.e. wing nuts, birthers, creationists, bat-sh*t crazies, Elvis sighters, and Sara Palin) love to use every fallacy of logical thought from misdirecting the burden of proof to misleading vividness to biased sampling and ad hominem tactics to attack the prevailing theories (hereafter known as “reality”). All they appear to need or hope for is the slightest bit of proof or half-truth or plausibility for their alternate theory to blow the entire issue wide open and the establishment theories will collapse like a house of cards.

This strategy is especially true for anti-vaccine conspiracy theorists who ignore the mountains of evidence* for the safety and efficacy of childhood vaccinations and instead point to a scant few studies that, though far from definitively proving a link between vaccines or thimerosal and autism or other neurodevelopmental disorders, do appear to suggest a possible connection.

Popular Mechanics took a closer look at many of these studies and found several serious credibility problems including at least three studies that were connected to the now discredited father of the MMR-autism-link theory, Dr. Andrew Wakefield (formally of the UK), one study that appeared in a non-independently peer reviewed publication, several studies authored by a geneticist who regularly provides “expert” testimony in court cases alleging vaccine induced injury, and one study that appeared in the journal of an anti-vaccine organization. This is equivalent to every study that showed the safety and efficacy of vaccines appearing in journals and publications owned by pharmaceutical companies and vaccine makers or in journals edited by researchers employed by vaccine makers.

And then there are the quality and accuracy issues. One study commentary falsely claimed that the symptoms of mercury poisoning and autism are very similar. There are hypotheses of a neuro-toxin caused by the MMR vaccine that is supposed to cause the autistic spectrum of disorders but none is ever identified or isolated. Studies point to statistical connections between increasing numbers of childhood vaccines and the increasing diagnosis rate of autism but don’t propose any plausible mechanism to explain this. One study found that the ethylmercury in thimerosal may accumulate in the brain more than methylmercury from environmental sources (like fish) but this study was done in monkeys and never duplicated in humans. Another study looked at the toxic effects of thimersoal on tissue in vitro but even regular tap water can be made to kill human cells in a petri dish and animal model studies and in vitro study results do not at all automatically apply to humans. Then there is this,

In perhaps the most telling sign that the mainstream scientific community and the anti-vaccination movement (and the studies it relies on for credibility) are not on the same page: between the 175 references in the Medical Veritas study [The danger of excessive vaccination during brain development: the case for a link to Autism Spectrum Disorders] and the 39 referenced in the Clinical Infectious Diseases literature review, there is, shockingly, only one study that appears in both: Andrew Wakefield’s now retracted 1998 Lancet study.

Multiple anti-vaccine studies that provide little proof or plausible mechanisms for their claims and they all reference each other instead of mainstream studies. That’s a circular definition. It’s another fallacy like the claim that God exists because the Bible says so.

The first problem with the anti-vaccine movement’s “house of cards” strategy is not understanding how science works. Though it does happen, it is rare for a single study to be a paradigm changer and in almost every case the study is well designed and opens up an entirely new area of research that includes several ever larger studies that confirm and expand upon the results of the initial study. More often than not, the results of multiple studies on a topic contradict each other but this does not mean that one or both sides are correct or wrong. Often it takes one or more “meta-analysis” to wade through the data from different studies that use different methodologies on different study populations to reach some type of statistical conclusion. The fact that a few studies appear to suggest an MMR or thimerosal link to autism does not definitively prove anything, nor does it negate the data of much larger and better designed studies.

The second problem with this strategy is in assuming that the prevailing establishment theories on the safety and efficacy of vaccines really and truly constitute a house of cards based on flimsy to little evidence that is ready to buckle and come crashing down at the slightest touch of the truth. Obviously this has not happened which means that what the anti-vaccine movement has in its study arsenal is not really the truth and/or that mainstream vaccine theory is a solid bedrock of repeatedly tested and confirmed evidence and data.

Of course, the conspiracy come into play when the theorists claim that the establishment is suppressing the truth by ignoring or suppressing their study results. Of course they never prove that that this “suppression” is from efforts to prevent the truth from coming out and not because their studies are junk.

Perhaps a little comparison in what a successful scientific paradigm change looks like is in order. For over 80 years, the prevailing theory in the medical field was that excess stomach acid is the cause of stomach ulcers. Though it had been proposed that a bacterial infection might be a cause, it was not until 1982 that Australian physicians Barry Marshall and Robin Warren were the first to isolate the bacterium Helicobacter pylori and find that it is a significant cause of gastritis and peptic ulcers in humans. Initially they met a significant amount of resistance from the scientific community and it took several years for their study to be published and start to be accepted. Hundreds of follow up studies confirmed and expanded upon their results and in 2005 they were awarded the Nobel Prize in Medicine for their discovery that changed our understanding and treatment of stomach ulcers. In contrast,  Dr. Wakefield’s Lancet study and MMR-autism theory was decidedly not followed by a ever growing body of successive experimental, clinical, and epidemiological evidence (quite the contrary) but the study itself was retracted in 2009 and Dr. Wakefield lost his UK job and currently works in Texas without a medical license.

That’s quite a contrast!

*Time trends in autism and in MMR immunization coverage in California. (JAMA 2001 Mar 7;285(9):1183-5), A population-based study of measles, mumps, and rubella vaccination and autism. (N Engl J Med 2002 Nov 7;347(19):1477-82), Thimerosal and the occurrence of autism: negative ecological evidence from Danish population-based data. (Pediatrics 2003 Sep;112(3 Pt 1):604-6), Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis (BMJ 2001 Feb 24;322(7284):460-3), No evidence for a new variant of measles-mumps-rubella-induced autism (Pediatrics 2001 Oct;108(4):E58), Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association (Lancet 1999 Jun 12;353(9169):2026-9), Neurologic disorders after measles-mumps-rubella vaccination (Pediatrics 2002 Nov;110(5):957-63), MMR and autism: further evidence against a causal association (Vaccine 2001 Jun 14;19(27):3632-5). Association of autistic spectrum disorder and the measles, mumps, and rubella vaccine: a systematic review of current epidemiological evidence (Arch Pediatr Adolesc Med 2003 Jul;157(7):628-34).

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