Sunday, November 28, 2010

Does a Link Exist Between the MMR Vaccine and Autism?

This is my English term paper, dealing with the supposed vaccine and autism link.  I feel it compares well with my last term paper.

In 1998 Alan Wakefield was the lead author of a paper that presented the possibility of a link between the measles, mumps, and rubella (MMR) vaccine and autism spectrum disorders.  This paper was widely reported on by the media, which, in turn, caused a significant drop in vaccination rates.  That drop caused an increase in measles and mumps, with some cases being fatal.  The paper also spurred a large amount of further research to be done on any possible link between the MMR vaccine and autism.  To date, no other credible links have been found.  In addition, the original paper has been retracted by ten of the thirteen coauthors and the journal that published it.  Despite this, there exists a great deal of fear and uncertainty about vaccines and autism among the general public.  Some of this is spread by ignorance, while some is spread by malicious motivations.  Regardless of the campaign to discredit vaccines in the public's eyes, it is clear that no link exists between vaccines and autism.

The paper which first proposed a link between the MMR vaccines and autism, was published in the British journal The Lancet in February of 1998.  In the paper the authors admitted “We did not prove an association between measles, mumps, and rubella vaccine and the syndrome described” (Wakefield et al. 641).  This, however, did not stop the authors from alleging a link between the MMR vaccine and autism based solely on anecdotal evidence provided by parents.  This questionable evidence, based on just twelve sets of parents, was the only link ever provided between the vaccine and autism.  Unsurprisingly, the paper's results were not reproduced by any of the many subsequent followup studies.

Many laymen have a very poor understanding of the scientific method and the principles on which it operates.  To many, if a study purports a link between two things, then that is an answer.  However, to the scientist, this is merely the beginning.  Rather than rely on lone experiments and studies to provide answers, the scientific method is based upon the dependency that experiments and findings be reproducible.  If someone cannot verify, for themselves, the findings of a study or experiment, then those findings should be questioned.  To some degree, this requirement to verify for oneself the results is lessened if the results have been verified by a large group of others independently.

In the case of Wakefield's MMR vaccine study the media did not wait for subsequent confirmation, or, in this case, refutation, of the hypothesis that the MMR vaccine was linked to autism.  Instead, they exploited the fear and ignorance people had, knowing that a fearful audience would be a captive audience, and spread the story.  To worsen the situation, reporting of scientific studies rarely does an adequate job of conveying the actual findings to people.  Often, possible links under specific circumstances are simplified into causes.  Links which are barely scientifically significant will be inflated into direct causes.

This was the case with the reporting of the MMR vaccine study.  The link between the MMR vaccine and autism was not even directly found by the study.  Instead, it was inferred from a handful of parents' casual observations.  Anecdotal evidence has no place in a scientific study.  Rigorous repeatable wide scale tests are the basis for any serious results.  The problem with anecdotal evidence is that it is easy to find anecdotal evidence of just about anything.  If one takes two fairly common events, e.g., the MMR vaccine and autism, it is easy to find a dozen examples where it seems obvious that one caused the other.  This is a consequence of simple probability.  There are millions of people with autism, and virtually all of the many millions of people in the developed world receive the MMR vaccine.  Given a pool of millions to choose from, it would be trivial to find any routine event that seemed to occur suspiciously close to the onset of autism symptoms.  In the case of the study in question, many of the parents claiming a link between the MMR vaccine and their child's autism were suing the vaccine manufacturers.  In a sense, these parents had selected themselves by making their belief in the autism-vaccine link public.  It is not surprising then, that when these same parents were selected for the study that they held a common belief that the MMR vaccine was linked to autism.

The link between the MMR vaccine and autism was tenuous at best.  However, this tenuous link was the only evidence the media needed to promote the story.  Around 2001 the media hype in the UK was gaining its full momentum.  During this time, British Prime Minister Tony Blair was asked if he had his son Leo vaccinated from MMR.  He refused to answer to protect the child's privacy.  The media subsequently reported on this refusal in great detail.  Reports about the MMR vaccine from January to September of 2002 mentioned Leo Blair 32% of the time, while Wakefield was only mentioned in 25% of reports (Economic and Social Research Council 22).  In addition, the media consistently avoided mentioning the overwhelming evidence for the safety of the MMR vaccine:
The bulk of evidence suggests that the MMR vaccine is safe – as opposed to the well established risks of the diseases themselves. The use of such evidence to was often used to ‘balance’ Wakefield’s claim – although not, perhaps, as widely as might have been expected...half the television reports on the issue referred to such evidence...Similarly, over a third of all TV reports mentioned that the MMR vaccine is regarded as safe in the 90 countries in which it is used. (Economic and Social Research Council 22)
There was also a lack of criticism of Wakefield's weak claims by the media: “Wakefield’s claims were not comprehensively or systematically challenged in media coverage...the weakness of empirical evidence in support of Wakefield’s claim was never fully aired” (Economic and Social Research Council 23). By neglecting to report on the prevailing consensus in the scientific community that vaccines were safe, the media was very much responsible for the controversy that followed, and continues to this day.  This tendency to prefer fear based speculation over the more mundane facts is a result of the media's desire to increase viewership at any cost.  Much of the blame for the mistrust the public feels in vaccines today can be placed directly on the media.

However, while the media is partially to blame, the person who deserves the lion's share of the blame is Alan Wakefield.  Wakefield, who is no longer a doctor after having his medical license revoked by the UK's General Medical Council, was the primary catalyst for the controversy.  He was the lead author of the original paper, and subsequently promoted the supposed link, and urged parents to question the safety of vaccines.  In July 2007, the General Medical Council began a hearing into charges of professional misconduct during the study that lead to the supposed link between autism and vaccines.  The charges specifically involved performing the study without approval from the hospital's ethics committee, and performing unnecessary, and invasive medical procedures on the children during the study.  However, perhaps the most damning charge was that he accepted hundreds of thousands of dollars from a law firm that was preparing to sue the MMR vaccine manufacturers.  He failed to disclose this payment publicly, or to either the hospital's ethical board or the journal the paper was submitted to.  On January 28th 2010, the General Medical Council ruled against him on all counts. Then, a few months later they revoked his medical license.  It was also discovered that Wakefield filed for a patent on a proposed safer MMR vaccine in June of 1997, prior to the original study (Deer).

Alan Wakefield's conflicts of interest could hardly be more significant.  Between hundreds of thousands of dollars paid to him directly by a lawyer interested in proof of harm caused by the MMR vaccine, and a patent application on an alternative method of administering the MMR vaccine, there should be little surprise that he claimed a link between the vaccine and autism.  It should also not be surprising that he then promoted the possible link, as well as promoted the alternative of individual applications of the MMR vaccine, since he stood to directly profit from his patent on that very method.  What should be surprising is that he still has the audacity to claim he is being persecuted, or that the government is trying to cover up his findings.  Wakefield, and his supporters, have attempted to use his discreditation to their advantage, by claiming in interviews that there is something akin to a large coverup being orchestrated by governments and research institutes the world over.  The total agreement of virtually every party that has looked at the possibility of a link between the MMR vaccine and autism, as well as the vast array of motivations and funding sources that these parties have, makes the idea of a mass conspiracy absurd at best.

As stated above, the cornerstone of scientific research is repeatable results.  The original study linking the MMR vaccine and autism and the following media attention sparked an abundance of studies looking for this link, as well as other possible links between vaccines and negative health effects.  These studies have overwhelmingly found no such links.  Some studies have looked at the countries where thimerosal, a mercury based preservative which has been claimed, by some, to be the cause of autism in vaccines, has stopped being used:
this study took advantage of the cessation of thimerosal use in Denmark and Sweden in 1992 to conduct a before and after comparison of the incidence or case numbers of autism. In both countries, autism increases throughout the years 1987-1999, contrary to the decrease in autism that would be expected after 1992 if thimerosal exposure was related to autism. The increasing trend for autism is most notable in Denmark where the number of autism cases rises substantially even after the discontinuation of thimerosal use. (CDC 1)
Other studies have looked for a link between the MMR vaccine and a large population, but have not found any such link: “The Danish study, which followed more than 500,000 children, over 7 years, found no association between the MMR vaccination and autism” (CDC 3).  A separate study found no link between the administration of the vaccine and the onset of autistic symptoms: “The study found that the overall distribution of ages at MMR vaccination among children with autism was similar to that of matched control children” (CDC 4).  Wakefield's original paper claimed that the MMR vaccine caused gastrointestinal tract disorders, and that these disorders were, in turn, the cause of the autism.  He also claimed that measles RNA could be found in the gastrointestinal tract of children with autism where this had occurred.  This link too was disproved by a study:
Laboratories evaluated bowel tissues from 25 children with autism and GI disturbances and 13 children with GI disturbances alone (controls); only 2 biopsy samples with measles virus RNA were found, one in the autism/GI group and one in the control group, showing that the presence of measles virus sequences was not associated with an autism diagnosis...Samples were analyzed in three separate laboratories blinded to diagnosis, including one laboratory wherein the original findings suggesting a link between measles virus and autism had been reported in 1998. (CDC 4)

Finally, a Japanese study from 2005 took advantage of the fact that the MMR vaccine had been discontinued in Japan in 1993 due to minor health problems unrelated to autism, including the administration of vaccines after their expiration date.  The version of the MMR vaccine that was used in Japan was different from the one used elsewhere.  Despite the relatively minimum threat posed by the MMR vaccine, the scare caused people to avoid it, and the government had to remove the requirement of it from school children.  Because of this, Japan is currently the only developed nation with widespread measles outbreaks—hundreds a year in recent years (Public Health Agency of Canada).  While unfortunate for Japan, this provides a good opportunity to observe what would happen to the autism rate if the MMR vaccine was stopped in other countries:
The MMR vaccination rate in the city of Yokohama declined significantly in the birth cohorts of years 1988 through 1992, and not a single vaccination was administered in 1993 or thereafter. In contrast, cumulative incidence of ASD up to age seven increased significantly in the birth cohorts of years 1988 through 1996 and most notably rose dramatically beginning with the birth cohort of 1993. (Honda et al.)
These studies all agree that there is no link between autism and the MMR vaccine.  There is no shortage of other studies that say the same.  There is no need to cherry pick studies that support this view.  Any time a large population is looked at, any apparent link quickly disappears.  The only time that a possible link can be finessed out of the data is when a very small sample is looked at, such that virtually any arbitrary connection could be found if it were being looked for.

Why then, given the mountain of evidence disproving any link between vaccines and autism is there still any debate or controversy?  Unfortunately, humans are predisposed to believe things they feel they have witnessed with their own eyes.  If a person has seen one of these consequences, which are unlikely individually, but virtually certain in the large-scale, they will tend to believe in the existence of a link, even if it is refuted by many rigorous scientific studies.  A parent with an autistic child will be very emotional over the subject, and rightfully so.  However, emotion is known to cloud rational thought.  Faced with the choice between a concrete link they can understand that caused their child's autism, and an open-ended unknown reason, many will choose the answer they can better understand, even if that answer conflicts with factual evidence.  There is also a desire to have a person to blame.  By linking the MMR vaccine and autism, parents can blame the doctors and scientists that said the vaccine was safe.

In addition, the controversy over autism has become fueled by celebrities, many of whom have come out against vaccinations.  On one side there are hundreds of scientists armed with dozens of large-scale rigorous scientific studies, and, on the other, there are a handful of celebrities with no evidence beyond feelings.  The choice is easy in a rational light.  However, many choices in people's daily lives are not rational.  Entire industries exist purely due to people's tendency to behave irrationally.  As one brief example, casinos and lotteries are always weighted against the player.  A simple bit of mathematics will show conclusively that the player will lose in the long run.  Despite this, there is no shortage of people willing to give their money to casinos and lotteries based on the irrational believe that they will come out ahead.  With this in mind, it is perhaps easier to imagine how people could choose to accept the celebrity's charisma over the scientist's facts.

Still, some argue that the autism rate has gone up dramatically in recent decades.  This does coincide with an increase in vaccinations.  If vaccinations are not the cause, then what is?  The answer is that many children who are currently diagnosed as autistic would have been previously diagnosed with a more generic or catch-all disorder, or often simply not diagnosed at all.  In the early 90s, the diagnosis of autism was replaced with autism spectrum disorder.  The new diagnosis reflected a greater range of autism, replacing the binary yes or no diagnosis of the past.  Immediately, many children who previously would not have been diagnosed at all, were said to have a mild form of autism.  As more and more doctors began to use the new system, the rate of diagnosis went up.  This is a rather obvious effect of the changing definition, and, in retrospect, it seems like it would be hard to not come to this conclusion.

Still, some are not convinced of the safety of vaccinations.  They argue that it is better to be safe than sorry.  Some propose simply delaying the vaccinations, and spacing them apart to lessen any effect the combination of them may have.  This, on its face, may seem to be a reasonable precaution; however, there are problems with delays.  Vaccines provide an actual proven benefit in that they protect from deadly diseases.  It is no secret that children are more susceptible to diseases in general.  By delaying the administration of vaccines, one only extends the time a child is vulnerable to a particular disease.  For an example of the effect this delay can have, one can look at Japan.  As stated above, Japan has largely abandoned the MMR vaccine out of fear.  However, even before abandoning the vaccine it was common practice to delay the administration of it to later in the child's life.  The BBC reports that “Deadly epidemics of measles are far more common in Japan than the UK. The [Japanese Ministry of Health] says that is because children are often vaccinated much later” (Scanlon).

In addition to the fact that delaying vaccination increases the risk of disease, the mind-set of simply being safe rather than learning the facts and making the correct decision is the wrong one.  People are quick to recommend a cautious delay when faced with unknowns.  However, these unknowns are only unknown to the layman.  If one took the time to research the facts independently, the conclusion would be the same as the professionals had reached.  No one says one must blindly accept what one is told by scientists as fact.  Indeed, questioning everything is one of the foundations of the scientific method.  This does not mean that one can just ignore evidence that disagrees with one's beliefs.  If one is unwilling to research the topics personally then the only other choice is to just accept the expert's opinions  The mindset of better safe than sorry is a perpetual roadblock that only serves to impede progress.  Edward Jenner is famous for boldly acting on his hypothesis that infection with cow-pox would provide immunity to smallpox, a much more serious disease.  His confirmation of this fact is viewed as the groundwork for all modern immunology.  Additional delay, and the better safe than sorry mindset, would have caused literally millions more to die.  It is wrong to think that blindly trying random solutions is the correct course of action.  However, a balance must be struck between recklessness and being suffocated by caution.

The link between the MMR vaccine and autism does not exist.  It was proposed and promoted by a man guilty of medical misconduct, and who had numerous conflicts of interest.  The link was subsequently retracted by almost everyone who had anything to do with it.  The media is largely responsible for spreading the story, while ignoring the evidence that contradicted it.  A plethora of studies followed and, virtually without exception, they failed to find any link between vaccines and autism.  The scientific community and rational people have unanimously agreed that no link exists.  Only misinformation from those who stand to profit, and the ignorance of, possibly well-intentioned, celebrities continue to breathe life into this myth.  Suggestions of caution are unnecessary, and indeed, will cause more harm than good.  The link between autism and vaccines has been proven conclusively and irrefutably false beyond all reasonable doubt.

Works Cited:
Deer, Brian. "Royal Free's "anti-MMR" Products - Brian Deer." Brian Deer - Web. 03 Nov. 2010.

Hargreaves, Ian, Justin Lewis, and Tammy Spears. "Towards a Better Map: Science, the Public and the Media." (2002). Print.

Honda, Hideo, Yasuo Shimizu, and Michael Rutter. "No Effect of MMR Withdrawal on the Incidence of Autism: a Total Population Study." Journal of Child Psychology and Psychiatry 46.6 (2005): 572-79. Print.

Public Health Agency of Canada. Measles Outbreak in Japan - Travel Health Advisory -Public Health Agency of Canada. Public Health Agency of Canada (PHAC) | Agence De La Sante Publique Du Canada (ASPC). 1 June 2007. Web. 03 Nov. 2010.

Scanlon, Charles. "BBC NEWS | Asia-Pacific | Why Japan Stopped Using MMR." BBC News - Home. 8 Feb. 2002. Web. 03 Nov. 2010.

United States. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention: Immunization Safety and Autism. 2009. Print.

Wakefield, A., S. Murch, A. Anthony, J. Linnell, D. Casson, M. Malik, M. Berelowitz, A. Dhillon, M. Thomson, and P. Harvey. "Ileal-lymphoid-nodular Hyperplasia, Non-specific Colitis, and Pervasive Developmental Disorder in Children." The Lancet 351.9103 (1998): 637-41. Print.

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