Autism, Vaccines, and Shifting Goalposts

08Jun09

This blog has, admittedly, been somewhat silent of late. For that I apologize. A perfect storm of exams, the real-life issues, and perhaps more than a little burnout from explaining to friends and associates that no, Swine Flu does not mean the world has come to an end.

So what does it take to rouse the author from his slumber, to compel the stressed and slightly underfunded dragon to leave his cave? Sadly, nothing exotic, merely stupidity on the internet.

Today’s post is inspired by Orac over at Respectful Insolence, or more accurately a post and the ensuing comment section made over the weekend. Particularly the words of the good Dr. Jay Gordon – or someone claiming to be him. Its yet another example of the constant, never ending and profoundly irritating argument tactic with the Anti-Vaccination crowd: The “reasonable calls for more study”.

Usually, this comes in some form of “I’ll change my mind when I see a prospective study!” or some other suggestion that the mountain of epidemiological evidence refuting the link between autism and vaccination is insufficient, but if they only had one more study…

I find this profoundly disingenuous. Leaving aside that they almost assuredly wouldn’t follow up on their promises even if such a study was performed, they’re asking for studies no legitimate, sane epidemiological or biomedical researcher would perform, or are so impractical as to never be funded.

In that particular thread, it was a “prospective” study. That flawed terminology is something we’ll leave for another day. What he means is a prospective cohort study, where the outcome (in this case autism) is unknown at the time of exposure assessment (in this case, vaccination status), and then study subjects are followed through time to see the risk of the development of autism in both groups. Some birth cohort studies should be able to meet this, but undoubtedly, someone will point out some nagging, inconsequential problem that means yet another negative study doesn’t count. Or I suspect the following to happen: Such a study (which are usually very expensive) comes out with a negative result, and the goalposts for the anti-vaccination movement shift once more. After all, cohort studies can show only correlation, not causation, and what they really meant they needed was a randomized control trial (RCT). And here’s where things get ethically dubious.

RCT’s, which most people mean when they say ‘Clinical Trial’, take a group of study subjects and randomly assign them to an exposure category. In this case, some of the study subjects would be given vaccines, and others wouldn’t, through random assignment.

Anyone seeing the problem yet?

We’re going to take thousands of infants and newborns (autism is a rare enough disease that it would take many thousands of babies to get a sufficiently large sample size) and refuse to administer known, life-saving vaccines, in order to study a relationship that currently has no sound epidemiological support.

We’ll never see a study like that. It wouldn’t get funded. I highly doubt any researcher worth their degree would even propose something like that. And I cannot imagine an Institutional Review Board anywhere would allow that kind of risk to newborn children with no reasonable chance for the advancement of science or children’s health.

The call for more studies, and especially randomized trials, on the part of the anti-vaccine lobby is, at best, a rhetorical flourish, a tactic meant to look like they’re on the reasonable side of asking for more evidence, and its just those mean, Establishment Hack doctors refusing to do the science. At worst, its a genuine request to put thousands of children (both those in the study, and those put at risk due a new pool of thousands of unvaccinated children) at risk of life-altering, and often fatal, childhood diseases in order to prove a claim that has no meaningful basis in reality.

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One Response to “Autism, Vaccines, and Shifting Goalposts”

  1. 1 Joseph

    An observational dose-response study would be doable. Some kids get vaccinated more than others, so they could look at the relationship between number of vaccines and developmental outcomes.

    It’s not perfect, like an RCT, but the socio-economic and cultural confounds could be controlled for by blindly screening the children for ASD (rather than relying on diagnoses sought by the parents.) It would not be possible to control for biological or environmental confounds too easily.

    The current anti-vaxer hypothesis is “too many – too soon,” so a dose-response study should be more than adequate to test it. It’s not “one vaccine is just as likely to cause autism as 10 vaccines.” So a fully-unvaccinated vs. vaccinated study is clearly not necessary. Though that will likely be the first excuse in the event the study is negative.


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