Vaccines are not associated with autism

Vaccine Hesitancy Series: Where did this concern originate? Why does it persist? What data do we have that shows there is no association? Read more to find out.

As I mentioned in my last post, I want to address concerns people have regarding vaccination. It will take me time to get to all of them, so please be patient and understand I am only tackling one topic at a time! I also understand this is a heated topic, I would appreciate you remembering I am a human and treating me with respect in the comments, even if you disagree with me. I will treat you with respect even if I disagree with you.

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Today’s post is going to tackle the false belief that vaccines cause autism. 

First though, I want to make some important general comments. The first is that those in the autism community have long said that they find it harmful that some people state that they think it is worse to be autistic than negatively impacted from an infectious disease (here is a post about consequences of infection for reference). This is a valid point and I think it is important to listen to those within the autism community when they share these insights. 

It is also clear that autism is at least partly genetic as we see it running in families and there have been some genetic variations associated with autism. However, the exact mechanisms behind its development are unknown. My post is not focusing on these other factors that may be involved in autism (I can work on that for a future post if people want that). I am focusing here on where the rumor of an association of vaccines with autism started and the data we now have that robustly supports that vaccines are not associated with autism. 

Where did this rumor come from?

Since vaccines have been available there have been people skeptical and concerned about their use. However, most people tie this particular rumor back to  Andrew Wakefield, a now discredited scientist. Wakefield published a now retracted case series claiming there was an association with the measles, mumps and rubella vaccine (MMR) and behavioral regression. There has been tons of work written on this whole situation (example here, here and here). I want to give you two examples about why this paper was problematic. 

First - this was based on only 12 patients. Yes that’s right - 12. Not 100, not 1,000, 12. I have often mentioned in my prior work that papers published on a small subset of people need to be taken with a grain of salt until larger studies can verify. This is because humans are complicated. We live very different lives from each other and have very different genetics. This means you need larger data sets to be sure any potential associations are not simply due to chance. 

There were even more ethical issues with the study that made it unreliable. Once an investigation was launched the Britain's General Medical counsel found that the 12 participants in the study were hand selected and already involved in a lawsuit against vaccine manufacturers before the study was done. Yes, you read that right. To make it worse the lawyer was paying Wakefield.

It doesn’t stop there, one of the fathers was co-founding a ‘safer’ measles vaccine alternative with Wakefield. There are many many ethical issues with the way this study gathered its participants. It is shocking. 

However, this study received a lot of media attention and the misinformation spread widely. So scientists have spent many years (and money) since then conducting studies to verify and subsequently reassure parents that there is not an association between autism and vaccination. 

So what data do we have that there isn’t an association?

A lot. Many follow up studies have been done. These have ranged from smaller studies to larger studies with hundreds of thousands of people and these have all found no association. 

For example, one study published in 1999 looked at 498 cases of autism in a specific school district in the UK. This study found that autism diagnoses had been steadily increasing with no change in the rate of increase after the introduction of the measles vaccine. 

Since then even more studies have been done that have found no association. A meta-analysis published in 2014 found no association between vaccines and autism. A cohort study published in 2019 that looked at 657,461 children in Denmark and found no association. A systematic review of the literature published as a Cochrane report in 2020 included 23,480,668 participants and also found no association of the MMR vaccine and neurodevelopment disorders. 

Now, some have taken this rumor further and blame vaccines or specific ingredients in general. Other studies have looked at other vaccines or vaccine components and have also found no association. I have compiled a google document with some of these studies as well as ones focused on the MMR vaccines in particular. While I could have missed some papers, this gives you an idea of the breadth of data we have that all comes to the same conclusion - that vaccines do not cause autism. 

In general, it is best to not rely on only one scientific study to form conclusions. The more data we have from different studies that come to similar conclusions the more certain we are that those findings are reliable. This is typically referred to as the body of scientific evidence. In this case there is tons of data with the same conclusion that vaccines are not associated with autism. 

So why does this rumor persist?

We have learned that false information tends to spread much more quickly than accurate information. It also is understandable that parents would like an explanation for the behaviors or symptoms they may be noticing in their child, so it is often easy to associate it with something new. Especially when regressions can occur in the period of life where kids are getting vaccinations. Blaming something like vaccines also gives parents a way of trying to control something that we actually cannot control at all. Since this rumor persists, new parents are often confused and unclear of how to access information and what to believe.

This is why anecdotes (aka stories) can be used to inform studies we want to set-up or question we want to ask, but we cannot use them as data in and of themselves. The body of evidence available on a topic helps us to make informed decisions, and to evaluate population level risks vs benefits. We are lucky to live in an age where we have many independent studies on this topic coming to the same conclusion. 

Parents want to be sure they are making the best decision for their kids, the type of false noise around vaccines and autism make that hard for parents who are trying to do their best.

How I wish conversations would go

I mentioned in my last issue that when my mom had concerns she didn’t get answers and wasn’t provided an opportunity to have a conversations with the providers or others about vaccines. I wish the beginning of these conversations with providers or other trusted messengers (friends of the person, scientists etc…) would go something like this.

Parent: “I am not sure about getting my child vaccinated. I have heard they may be associated with autism or other issues.”

Pro-vaccine person: “I understand you want to do the best for your child. There is so much false information about this topic that it is hard and scary to navigate. There have been a lot of studies done over the last 20 years that have shown there is no association between vaccines and autism. Would you like links to these papers or resources? What kind of information would help you think through this decision? I am happy to help connect you to resources or others to answer your questions".

Then from there have an open conversation. I know this isn’t always possible, especially if one or both parties isn’t willing. I also know this takes time.

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Next Up/Housekeeping

Please feel free to suggest topics below or via email. These posts take a lot of time and thought given how volatile these issues are so also expect some breaks for other topics in between.