Vaccines and Autism: A Tale of Shifting Hypotheses

ResearchBlogging.orgA paper coming out in the next issue of the journal Clinical Infectious Diseases addresses the question of the link between vaccines and autism. This new review article examines three hypotheses linking vaccines to autism:

(1) the combination measles�mumps�rubella vaccine causes autism by damaging the intestinal lining, which allows the entrance of encephalopathic proteins;

(2) thimerosal, an ethylmercury�containing preservative in some vaccines, is toxic to the central nervous system; and

(3) the simultaneous administration of multiple vaccines overwhelms or weakens the immune system.

[This is a repost in honor of Get Your Flu Vaccination Week. Which is now. Did you get your vaccination yet?]

The MMR hypothesis was first advanced in a paper by Andrew Wakefield, in 1998. The present study suggests that Wakefield’s MMR – Autism link was flawed for a number of reasons. Methodologically, the studied cohort was self selected among a large population. The MMR vaccine is given at about the same time autism is often diagnosed, exacerbating a confirmation bias effect. The MMR-Vaccine theory relies on an intestinal route for encephalopathic substances, which would be indicated by some kind of G.I. symptoms prior to the autism, but this was often not the aetiology of the disease. There are other problems with this study as well.

The paper examines other MMR-Vaccine link studies and finds them at fault as well.

The Thimerosal link hypothesis asserts that ethylmercury, an ingredient in Thimerosal, is the cause of autism. Thimerosal is an antibacterial that has been used for decades to preserve various vaccines, (not including MMR, which is a live vaccine). Although there are several reasons to not think that Thimerosal can cause autism, several studies have been conducted to test the relationship (probably not a bad idea given the importance of this problem) and all of these studies failed to link Thimerosal to autism. What is especially convincing are studies that show a complete discordance between Thimerosal use and autism.

In Sweden and Denmark, researchers found a relatively stable incidence of autism when thimerosal�containing vaccines were in use (1980-1990), including years when children were exposed to as much as 200 μg of ethylmercury (concentrations similar to peak US exposures) [22]. However, in 1990, a steady increase in the incidence of autism began in both countries and continued through the end of the study period in 2000, despite the removal of thimerosal from vaccines in 1992.

The third hypothesis …. that too many vaccines stress the patient and ultimately cause autism to develop … was also found to be flawed.

Vaccines do not overwhelm the immune system. Although the infant immune system is relatively naive, it is immediately capable of generating a vast array of protective responses; even conservative estimates predict the capacity to respond to thousands of vaccines simultaneously… The immune response elicited from the vast antigen exposure of unattenuated viral replication supersedes that of even multiple, simultaneous vaccines…. Multiple vaccinations do not weaken the immune system. Vaccinated and unvaccinated children do not differ in their susceptibility to infections not prevented by vaccines … Autism is not an immuneâ?mediated disease. Unlike autoimmune diseases such as multiple sclerosis, there is no evidence of immune activation or inflammatory lesions in the CNS of people with autism…

The present study is, essentially, a meta study of twenty or so other studies that in combination seem to force the conclusion that the three hypotheses mentioned at the outset do not explain an apparent increase in autism cases. The authors suggest that the apparent increase in cases is a matter of changes in reporting, although as we have seen in other studies, that is contested.

Full disclosure: One of the paper’s authors is “…a coinventor and patent coholder of the rotavirus vaccine Rotateq and has served on a scientific advisory board to Merck.”

Jeffrey S. Gerber, Paul A. Offit (2009). Vaccines and Autism: A Tale of Shifting Hypotheses Clinical Infectious Diseases, 48 (4), 456-461 DOI: 10.1086/596476

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8 thoughts on “Vaccines and Autism: A Tale of Shifting Hypotheses

  1. Not to mention that the data in the original MMR paper was falsified by Andrew Wakefield and the subjects were chosen from a lawsuit against vaccines.

    The rise in autism after mercury preservative was removed completely disproves that hypotheseis, yet it Will Not Die.

  2. Full disclosure: One of the paper’s authors is “…a coinventor and patent coholder of the rotavirus vaccine Rotateq and has served on a scientific advisory board to Merck.”

    Hahahahaha!!! But, of course!

  3. Its been proven, there is still mercury (levels high enough to be considered toxic) in the so called “mercury free vaccines”. THAT is why “it” will not die.

    The fact remains, those who supposedly “prove” autism (and a number of other conditions) are not related to vaccinations are those who have a STRONG financial tie to the vaccination manufacturers. They have been shown to falsify information and manipulate studies to show their agenda. If they admit that vaccinations cause harm, they would lose BILLIONS — for some reason, most cannot put two & two together but those ho research it can and THAT is why “it” will not die.

  4. Pamela, you are wrong. Are you wrong because you are ignorant, or are you wrong because you are politically motivaed, or are you wrong because you are delusional? I can’t tell.

    Mercury in vaccines is a) not toxic b) not in all but a few vaccines and c) in those vacines in which it is still used there is ALWAYS a way of getting the vaccine without mercury.

    I personally have no financial tie to the vaccination manufacturers. I have read ALL of the original research on this. And I am certain that the mercury in the form it has been useded does not get into human tissues, and I’m certain that the fact that when mercury stopped being used in vaccines autism rates did not drop at all. I am absolutely certain that you are wrong in what you are claiming.

    And, I warn you, this blog (the one you are reading now … my blog, not your blog, but his blog) is NOT a platform for vaccine denialism or woo. So you will now go away. Readers who are interested in knowing more about this issue can start by comparing your comment and mine, then entering their questions into the Skeptical Search Engine:

    where you will find woo-free information from several excellent sources.

    Pamela, you are doing something that is harming other people. But somehow I suspect you don’t lose much sleep at night. Someday maybe you’ll realize the damage you are doing.

  5. “However, in 1990, a steady increase in the incidence of autism began in both countries and continued through the end of the study period in 2000, despite the removal of thimerosal from vaccines in 1992.”

    i think it was “removed” in 1999, not 1992.

  6. Did you get to the last part of the article that says:

    “No studies have compared the incidence of autism in vaccinated, unvaccinated, or alternatively vaccinated children (i.e., schedules that spread out vaccines, avoid combination vaccines, or include only select vaccines). These studies would be difficult to perform because of the likely differences among these 3 groups in health care seeking behavior and the ethics of experimentally studying children who have not received vaccines.”

    No studies are conducted (for this bogus reason of “ethics” laughable coming from ex-Merck), therefore no conclusion either way.

    This “controversy” is laughable to me, if the (true) data is made available, a high-school kid can give great insight to it is 10 min (and for free). At least a necessary condition for the link. This is not rocket science, you see this all time, when you read for example “eating 1 serving of veggies /day decrease the risk of heart attack by 10%” (making it up).

    We use probability theory. Let the variables A=”autism diagnosed at age x”, V=”vaccinated”. Then the problem is to calculate:
    P( A | V ) versus P(A | non V) , where P( A | V ) means “probability of subject having A given he/she is V” . We use the entire US kid population under age x as sample population.

    Using conditional probability theory:
    P(A|V) = P( A and V) / P(V) and similarly P(A| non V) = P(A and non V) / P(non V).

    We just need the stats data. Now P(V) is known (probably the most tracked data by the gvt). Say if the vaccination rate is at 80% for some year, then P(V)=0.8 and P(non V)=0.2.
    Now the missing data, is the rate of (A and V) and the rate of (A and non V), which now we know we cannot have for “ethical reasons”.

    For example, if we find out that P(A and V) = 0.3 and P(A and non V) = 0.1, then
    P(A|V) = 0.4/0.8= 0.375 while P(A|non V) =0.1/0.2=0.5, which would mean that you are less likely to get A (autism) when you vaccinate then when you don’t by a ratio of
    37.5% to 50% . In this (fictitious) case, your odds of staying autism-free is to vaccinate.


  7. “P(A and V) = 0.3 and P(A and non V) = 0.1,”
    You do realize that
    P(A and V) + P(A and not V) = P(A), right? (Look up the law of total probability, or simply draw a Venn Diagram).
    This means that your imaginary scenario has 40% of the population autistic. Why use such unrealistic numbers?

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