Vaccines and Autism: Why the Controversy?

by Tania Houspian, PharmD 2011

VaccineThere is a tried and true medical procedure that is minimally invasive and takes a few seconds to perform. This procedure will help prevent dozens of diseases and aide in making the entire population healthier. The more people that undergo the procedure, the better it is for the health of the entire population. Like any procedure though, it has its risks. Do the benefits outweigh the risks? Would you choose to undergo this procedure?

That’s a question you always have to ask yourself when choosing to undergo any medical procedure. The risks and benefits need to be weighed.  More importantly the true risks and true benefits need to be weighed. Grandma thinks that her blood pressure medicine gives her gas but, as her children and grandchildren can confirm, Grandma had some serious gas long before she began taking blood pressure medication. Just because two things happen at the same time does not mean that one caused the other.  Correlation does not equal causation.

So what was the procedure we referred to above?

Procedure: Vaccinating Children

Benefit: Vaccines are the single best public health measure ever implemented in our society. They have been proven to prevent many diseases that, in the past, were the leading causes of death in young children.  Think Polio, for example.

Risk: Autism?

One in four Americans believes that vaccines cause autism. When anything becomes that engrained in the minds of a society, it warrants deeper examination. There are two main theories that aided in forming this widespread notion.

Theory #1:

Andrew WakefieldThe first mention of vaccines being a possible cause of autism was in 1998 by British gastroenterologist, Andrew Wakefield. Wakefield, along with 12 others, published a paper in which they put forward the theory that the measles virus in the measles, mumps, and rubella vaccine (commonly called the MMR vaccine) caused a “leaky gut.” They concluded that the leaky gut allowed toxic substances into the bloodstream that eventually ended up in the brain. In the paper they recommend separating the three (measles, mumps, and rubella) into separate vaccines. Wakefield called a press conference to let everyone know about his discovery and consequently triggered a panic in Great Britain.

Since then, Wakefield has not exactly been what we would call a respected member of the medical community. Ten of the co-authors on that paper retracted their involvement and have said they do not agree with the conclusions that Wakefield drew in his paper. The General Medical Council is also investigating Wakefield for scientific misconduct, specifically falsifying data.  Oh yeah, and Wakefield also forgot to mention that he was working on introducing a new measles vaccines to the market to compete with the MMR vaccine. Can you say conflict of interest? Hidden motives aside, Wakefield’s research methods have been accused of not only being flawed but also unethical.

Taking into account the fact that Wakefield has been publicly discredited and his paper deemed invalid, you would think this theory regarding the connection between vaccines and autism would have fallen by the wayside…and it hasn’t.  This is because it’s not that simple.  Many people believed Wakefield was on to something even if the science did not match his conclusions. Due to the number of vaccines children receive in the first three years of life (14 vaccines to be exact) many parents felt that there could be a connection.  Once the idea of a risk like this has been introduced, it’s difficult to get the idea out of people’s minds. Simply said, it’s always easier to scare people than to un-scare them.

Theory #2:

MercuryIn 1999 the US government published a report revealing three childhood vaccines (diphtheria, tetanus, acellular pertussis [a combo called DTaP]; Haemophilus influenzae type b (Hib); and hepatitis B) contained higher levels of mercury than previously thought. Thimerosal is the preservative used in these three vaccines and contains 49.6% ethylmercury by weight. An obscure medical journal took this finding and ran with it, publishing an article (without any scientific validity) saying that autism was a form of mercury poisoning.  This, of course, caused a huge uproar in the United States and propaganda like the image and chart included below (again, without scientific support; note the lack of references for the chart’s information).  In response, the Center for Disease Control reviewed numerous studies all finding that there is NO LINK between autism, vaccines, and mercury. Even though the CDC’s findings showed no connection between mercury and autism, the government still requested vaccine manufacturers to remove the mercury component from all childhood vaccines.  Since 2001, no childhood vaccines have contained mercury.  So let’s say the initial theory published by the obscure medical journal linking mercury and autism was correct (even though all the scientific evidence pointed the other way), then autism rates should have dropped dramatically after mercury was removed from all vaccines in 2001…and parents everywhere would be able to breath a sigh of relief. Well, it turns out that the exact opposite has happened. Autism rates have continued to rise since 2001. This simple fact should be enough to put the mercury-autism theory to rest yet many groups out there continue to vilify vaccines and anyone who dares step up to defend them.

Mercury – Autism Propaganda

Mercury Poisoning

Then why the controversy?

So why is it that, even though all the scientific evidence seems to point away from the connection between vaccines and autism, people still believe vaccines cause autism? Personal experience and temporal associations. One of the main driving forces amongst groups who believe vaccines cause autism are parents with children who have autism, which they begin to notice during the same period of time their children are receiving their 14 recommended vaccinations. Many parents first start to notice signs of autism when their children have developmental delays in speech. The MMR vaccine (which, by the way, never contained thimerosal) is given around 12-15 months of age, which coincides with the age most children begin to speak. So it seems that the most likely explanation is coincidence not causation. There are also many children who exhibit signs of autism prior to any vaccinations, further discrediting the link between vaccinations and autism.

What Now?

No one can belittle how difficult it must be for the parents of autistic children to witness their children’s developmental challenges. These parents need an explanation and, with so many people pointing the finger at vaccines, it’s a tempting to jump on the bandwagon. This approach, however, is not helping anyone. The focus of autism research has been and will continue to be on genetic causes of the disease.  This is the research that needs to be supported and perpetuated in order for real answers to be found and for meaningful interventions to be developed.

UK Measles CasesPeople seem to have become comfortable with how safe vaccines have made our society and forgotten that the illnesses they prevent can kill their children. These viruses continue to exist throughout the world and, without vaccination, we remain vulnerable to the epidemics they can cause. When Wakefield published his paper in 1998, parents in Great Britain stopped vaccinating their kids. The rate of vaccination dropped to 80% by 2003.  That same year, over 1,000 measles cases were reported in Great Britain. Similarly, in the United States there have been outbreaks of measles, pertussis, and Haemophilus influenzae Type B…all diseases that are preventable through vaccination.

References:

Fombonne,E. Thimerosal disappears but Autism Remains. Arch Gen Psychiatry. 2008 Jan;65(1)15-6

Gross L (2009) A Broken Trust: Lessons from the Vaccine–Autism Wars. PLoS Biol 7(5): e1000114. doi:10.1371/journal.pbio.1000114

Immunize.org, http://immunize.org. December 22,2009.

Miller L, Reynolds J. Autism and vaccination- the current evidence. J Spec Pediatric Nursing. 2009 Jul; 14(3): 166-72.

Thimerosal In Vaccines Questions and Answers. http://www.fda.gov/BiologicsBloodVaccines/Vaccines/QuestionsaboutVaccines/UCM070430#q5. December 26,2009.

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