Attribution between autism and vaccines has grown dramatically in the general public, from essentially no one sharing this belief 12 years ago to a large number of people believing this today. The effect is large enough to have substantially affected vaccination rates in countries like Britain, where rates of MMR vaccination have dropped substantially. This state of affairs necessarily has a lot of people trying to understand why this belief about autism spreading. There are many answers (such as the way information spreads across the internet with limited ability to control for reliability), I am sure. One of the most important of them likely has to do with another type of attribution.

If you surf the web, or watch local television, you will notice autism is receiving a lot of attention. And, those who are getting the attention tend to spend most of their time either claiming that autism is (parents) or is not (doctors) caused by vaccines. In fact, it seems like most parents that you see in the media think their child’s autism originated with vaccines. Therefore, many people who don’t know much about autism are getting swept up with these parents (they must know their children after all…) in the belief that vaccines cause autism.

The problem with this whole line of thinking is that the number of parents who think their child’s autism was caused by vaccines is quite low, and was much lower before the controversy became news. The general public has developed a bias against vaccines in large part because of 1) what stories the media chooses to cover, particularly since Andrew Wakefield burst onto the scene with his essentially fraudulent study, and 2) the fact that parents who believe vaccines caused their children’s autism, seem to be significantly more vocal and active than those who attribute the autism to other triggers or don’t attribute the autism to any external cause. Many individuals in the general public believe that vaccines cause most cases of autism, despite the fact that most parents of autistic kids don’t believe that to be the case.

The fact that relatively few parents of autistic children actually connect their child’s autism to vaccines has been demonstrated in several studies. In a study involving 177 children with language regression, 88% of whom were diagnosable with autism, researchers found the following: fifty-two families (29%) reported a trigger to the regression. The most common triggers reported included family stresses (n=23), such as the birth of a sibling (n=10) or moving (n=7), seizures (n=13), or infectious/immunologic triggers (n=14). More specifically, they found that only 8% (15 of 177) of parents attributed regression to immunization, compared to 19% who blamed the birth of a sibling, and 44% who blamed family issues in general.

In one study of 547 autistic children by Lingam et al, parents of 44 of the 106 children with detailed information on regression mentioned a specific trigger as a possible cause. The most common (13 children) was a household or social change such as the birth of a sibling, then vaccination (12 cases). Other triggers mentioned were: viral and bacterial infections (n = 7), seizures (n = 7), post-surgery (n = 2), and other causes (n = 3). Vaccines were the attributed cause of autistic regression in only 12 of 44 cases where a trigger for regression was mentioned by the parents (12 in 547 total parents).

In both these studies, a relatively small percentage of those parents whose child regressed into autistic symptoms (which is already less than a third of total cases) made an attribution between the autism and a vaccination. However, despite their more frequent occurrence, none of other reported triggers such as household stress are the subject of a media frenzy or congressional hearings.

I think there is another major factor at play that underlies this phenomenon – the fact that many people have a great distrust against government imposed, mandatory health care. It would seem to be a control issue. For the most part, we have little choice in getting our children vaccinated. Governments around the world have decided that public health is more important than individual choice, largely because of how herd immunity works. And, they have found various ways to force parents to get their children vaccinated (i.e. requiring vaccinations as a precondition to entering school). This seems to have caused a pretty large segment of the population to have developed a philosophical / political problem with vaccines (and other types of coercive health case, like fluoride), which has pushed along theories that implicate vaccines in negative health outcomes, like autism. A societal bias has developed that is exceptionally strong in many individuals (who are they to dictate to me that I have to… I make the decisions about my child’s health care!).