I hadn’t planned on blogging about vaccines again for a while. Really, I hadn’t. Even I realize the risk of beating the proverbial dead horse just one time too often. Also, It seems that I’ve been writing about antivaccination loons a lot lately, even more than usual. However, aside from a prime time spot for antivaccinationist propganda, the news has been mostly good, with study after study poking holes below the waterline in the hull of the rickety rustbucket of a boat that is the whole antivaccinationist belief that vaccines cause autism.
Here’s another one.
This time, in yet another in a series of slaps in the face to Andrew Wakefield, the antivaccinationist paid by trial lawyers to find evidence linking the MMR vaccine to autism, the better to allow lawsuits to proceed. Of course, his “evidence” for a link between MMR and “autistic enterocolitis,” published in 1998, was so incompetently obtained and written up that most of his coauthors ultimately disowned the study. Sadly, it was too late to prevent a wave of antivaccination hysteria to sweep the U.K., leading to a rapid drop in MMR vaccination rates and a massive increase in new measles cases, including at least one death.
In the nearly ten years since Wakefield almost single-handedly trashed the vaccination system in the U.K., no one has been able to replicate his findings. Now, hot on the heels of a study showing that thimerosal in vaccines is not associated with autism, making the rounds in the media is a study that examined the question of whether the MMR vaccine (which does not contain thimerosal) is associated with autism. Coming from Professor Gillian Baird at the Newcomen Centre for Child Development at Guy’s Hospital in London, it’s entitled Measles vaccination and antibody response in autism spectrum disorders.
Basically, the investigators tested the hypothesis that measles vaccination is involved in the pathogenesis of autism spectrum disorders (ASD. One prediction of such a hypothesis is that signs of a persistent measles infection or abnormally persistent immune response shown by circulating measles virus or raised antibody titers would be found in children with ASD who had been vaccinated against measles, mumps and rubella (MMR) as compared with controls. The methodology of the study was a community-based case control studying a cohort of 56,946 children born between July 1, 1990 and December 31, 1991 in 12 districts in the South Thames district of the U.K. At age 9-10 years, children with a diagnosis of ASD or a statement of special needs and the results used to identify a subset of 255 of the 1,770 children so screened who received an in-depth diagnostic assessment to identify characteristics of their autism or other learning disabilities. These were the subjects selected for the study. From these, blood was obtained from 101 with a diagnosis of autism or ASD and 55 special needs children with other diagnoses for comparison. The children with ASD were further examined for gastrointestinal symptoms or a history of regression. In addition, 98 children without a diagnosis of ASD or other learning disability were also recruited as controls. Although all of these children had been vaccinated, but some had not received both doses of the MMR. Ultimately adequate samples were obtained from 98 with ASD, 52 with a special needs diagnosis but no ASD, and a normal typically developing group (n=90).
So what did Baird and her colleagues find?
No correlations, nada, zip. There was no correlation between ASD cases and controls for measles antibody response and no dose-response correlation between autistic symptoms and concentrations of anti-measles antibody. There was no evidence of a differential response to measles virus in children with ASD, regardless of whether there was a history of regression, and controls. There was no difference between levels of measles virus detected and the presence of an ASD diagnosis. Of all the children, only one of the children from the control group had symptoms of enterocolitis, and there was no evidence of increased incidence of enterocolitis in autistic children with regression. This study was about as negative a study as you can get, and it’s consistent with two earlier studies. It was also the largest reported and characterized by well-defined criteria for regression. Moreover, a highly sensitive assay was used to assay measles antibody. One aspect of the study that may have had an impact on how the results turned out is that this was not blinded. Parents knew that the study was about MMR, which may have led to a bias in who agreed to enroll their children. Of course, if anything, such a bias, if it existed, would have made it more, not less, likely that this study would have found a difference between children with ASD and neurotypical controls, making the negative result of this study even more resounding. It was also noted that children with ASD or special needs were more likely not to have had both MMR doses.
Professor David Salisbury, director of immunisation at the Department of Health, said: “It’s natural for parents to worry about the health and wellbeing of their children and I hope this study will reassure them that there is no evidence linking the MMR vaccine to autism.”
Public health experts will be hoping this study can lay to rest the controversy.
The Department of Health stressed the quality of the study and in a statement said it had “linked very careful assessment and diagnosis of a child’s condition, with expert analysis of blood samples”.
Sadly, I doubt that even this study will lay to rest the “controversy.” It probably would if the debate were about science, but it’s not, and no amount of evidence seems adequate to persuade antivaccinationists. Nevertheless, this has been yet another in a long line of studies that have failed to support the claims of antivaccinationists that either thimerosal in vaccines or vaccines themselves cause or contribute to autism. Indeed, it’s becoming clear that they’re feeling the heat from all this negative data, to the point that their justifications and rationalizations are becoming increasingly divorced from anything resembling reality. Indeed, recently Mark Blaxill whined in a most hilariously self-righteous manner that the bloggers criticizing antivaccinationists are a bunch of meanies. Clearly, Blaxill must have limited or no experience with Usenet or other discussion forums if he thinks I’m mean–or that any other of the bloggers on “our” side are particularly mean–particularly in comparison to bloggers on “his side.” If anyone deserves the name “whackosphere,” it’s mercury militia bloggers. (John Best, anyone?) Meanwhile, Dan Olmsted is even more hilariously whining about being called out by Autism News Beat for his sloppy reporting and unsupported claims that autism is rare among the Amish and his implication that it must be because the Amish don’t vaccinate. (Never mind that the Amish are inbred, don’t use modern technology, live a rural, agrarian lifestyle, and have any number of differences when compared to the vast majority of Americans who do are not Amish–it’s so obvious that if a difference in autism prevalence between the Amish and the rest of us exists it must be those evil vaccines!)
The belief that either thimerosal in vaccines or vaccines themselves causes autism is a discredited idea. Contrary to the claims of antivaccinationists, it is a hypothesis that has been investigated extensively, the results of these studies being published in the peer-reviewed biomedical research literature. No reputable researcher publishing in a good peer-reviewed journal has presented convincing evidence (or, in most cases, even any evidence at all) of a link. It’s time to move on to other more promising areas of inquiry with regards to the causes of autism, because science has made it pretty much as clear as it is able to do that vaccines are not one of the causes.
To point this simple observation out strongly (and, yes, even sarcastically when certain members of the Ferrous Cranus sect continue to cling irrationally to mercury in vaccines or vaccines themselves as a cause of autism, no matter how much evidence is thrown at them that fails to support a link) does not, as one person has claimed, imply a “convenient rejection of our children’s health problems.” Far from it! It is because we are tired of seeing so much fruitless effort and expense wasted chasing after discredited hypotheses rather than more promising avenues of investigation. Moreover, as much as we can sympathize with the difficulties that many parents of autistic children have in raising their children and trying to find help for them, contrary to what some of them seem to think, their challenges and heartbreaks do not and should not immunize them from criticism when they promote antivaccinationist claims that are not supported by science. Criticism of the support of some of these parents for antivaccine pseudoscience is not a rejection of their children’s health problems, but rather a means of pointing out that they have gone down a blind alley in looking for reasons for their children’s condition and that they need change course. The contempt that I sometimes heap upon antivaccinationists comes from the knowledge that it is they who are clearly oblivious to the harm to all our children’s health that their views can engender.
Baird, G., Pickles, A., Simonoff, E., Charman, T., Sullivan, P., Chandler, S., Loucas, T., Meldrum, D., Afzal, M., et al, . (2008). Measles vaccination and antibody response in autism spectrum disorders. Archives of Diseases of Childhood DOI: 10.1136/adc.2007.122937