Are autism and vaccinations linked, after all?
I know that you are not one of the reasonproof individuals still running around claiming that vaccines cause autism despite the pile of scientific papers demonstrating that this belief is utter nonsense. In fact, I had been under the impression that even the most stalwart anti-vaxxer had abandoned this cause. However, as difficult as it may be to believe, recent events have proven that there are still some of them out there, standing steadfast and strong in their denial of science. If you should come across one of these people, approach with care. There is no telling what other odd and irrational beliefs they may have, and being stuck in conversation with them at a cocktail party may result in your rolled eyes “getting stuck like that”.
But anyway, I wanted to alert you to a recent publication, entitled “Immunization uptake in younger siblings of children with autism spectrum disorder” by Kuwaik et al. and published in the journal Autism on October 8, 2012. This work was conducted within a Canadian prospective study of autism, which included children diagnosed with autism, their younger siblings, and a matched control group. There are several important pieces of information provided by this study, which was designed to assess whether rates of immunization were different in siblings of children diagnosed with autism vs. controls. One of the findings of the paper is that autism is, in fact, statistically signficantly related to vaccinations after all…but probably not in the way that is expected by anti-vaxxers. In short, here are the two major results of the study.
1. In the population studied, parents of autistic children were significantly more likely to delay or decline vaccinations compared to those of non-autistic controls.
A total of 60.2% of children who had an older sib diagnosed with autism had delayed or declined MMR and/or DPTP (diphtheria, pertussis, tetanus, and polio); whereas only 9.2% of controls delayed vaccination, and all controls eventually received all vaccinations. Importantly, only 24% of the older siblings with autism had delayed or declined vaccination.
The public health significance of this finding is striking. The latter observation regarding differential vaccination rates within families is a key part of this analysis, as it strongly supports the concept that the misinformation about vaccines causing autism had a profound effect on the choice of whether to vaccinate children after an older sibling was diagnosed with autism. It must be noted, however, that the sample of families who had enrolled in this study may be biased, and that the rates of vaccination delay or refusal are likely to be lower among families with autistic children in the general population. We must also note that 40% of families who with an older sib diagnosed with autism fully vaccinated their younger children on time. Therefore, the paper should not be used to make generalized statements about how all families with autistic children make healthcare decisions.
Nonetheless, this finding provides strong evidence of the effect of Andrew Wakefield’s fraudulent paper and the subsequent adoption and promotion of vaccinations as a cause of autism by groups such as Generation Rescue. The findings also, finally, provide that elusive link between autism and vaccinations, in the sense that a diagnosis of autism is significantly associated with a decline in vaccination in later siblings.
2. In secondary analyses, the rate of autism was approximately double in younger sibs who had delayed (31%) or declined (33%) vaccinations as compared to those who were fully immunized on time (15%).
First and foremost reader, we must note that these results were not statistically significantly different from one another, and were secondary analysis. Thus, we must use caution in interpreting these data, as the authors themselves state in the paper. The numbers used for these calculations were relatively small, with 6/39 fully vaccinated younger sibs having been diagnosed with autism; 15/47 of those who had delayed vaccination; and 4/12 who had refused vaccination. The relatively small sample size indicates that caution is warranted in making sweeping conclusions about the idea that vaccinations may actually reduce the risk of autism. But it would certainly be fair to say that we now have yet another paper showing that there were no significant differences in the rate of autism between unvaccinated and vaccinated children.
We can now add yet another study to the catalogue of studies showing absolutely no association between vaccination and autism rates, though it does show an association between autism and vaccination rates. I wonder how many more of these will have to be produced before we can convince those last few holdouts who cling to a belief that vaccines cause autism despite all evidence to the contrary, and who do more damage than they can possibly imagine to the families of those with autistic loved ones.
Nevertheless, in my opinion, the most important aspect of this paper is the clear and deleterious effect of pseudoscientific information on vaccination rates. And it doesn’t just strike families with autistic members; rather, perpetuation of this type of misinformation has a broad-based and negative impact on public health overall.