The Vaccination Situation Pt. 2

Source: Myriams-Fotos on Pixabay

The Wakefield Paper

Hey y’all! Last week we took a quick look at vaccines and how they’re tested. Well today we’re going to take this a bit further and look at a specific study questioning the validity of vaccines, specifically, the MMR vaccine. Back in the 80s, Andrew Wakefield published a study that linked this vaccine to autism. However, some things were a little off… The paper has since been retracted, but we’re going to see exactly why.

For starters, the sample size of Wakefield’s study was just 12 children. Additionally, there weren’t any controls in the group at all. Isn’t that wild?!?! Instead they observed children in the hospital and drew their conclusions from that. Even crazier than not using a control, many tried and failed to replicate his results. For example, this NIH article shows a failure to replicate the results when using a control.

Madsen’s Update

Now, if we fast forward a little bit to 2002, Madsen took a look at this study and tried to replicate it. However, unsurprisingly, the attempt was unsuccessful and no link was found between the MMR vaccine and development of autism. With a much larger sample size, and better designed study, Madsen was able to easily prove that there was no direct link between the MMR vaccine and development of autism.

So what exactly was different or “better” about Madsen’s study compared to Wakefield’s? Well, for starters, Madsen used a population size of over 500,000 children. This helped removed the possibility of bias and gave many data points to further inform the research. He also had a control group, and found that when compared, there was no significant difference between them, proving that MMR vaccines do no cause autism. The reason for this follow up was because the Denmark government had a program where children were getting vaccinated young and they wanted to prove that it wasn’t harmful. They were successful, and fears were eased.

Relative Risk Ratio

To tie this all together, we can take a look at relative risk ratio to understand how Madsen concluded that the MMR vaccine was safe. To define this term, the CDC shows an equation that compares the risk of exposed and unexposed populations. Essentially, if the rate of contraction (in this case autism) is the same for the two populations, then there is no reason to believe there is any causation happening. This is because the treatment isn’t showing to increase the chances of what they are checking.

Now, we can take the relative risk ratio and apply it to Madsen’s research. Looking at the results, the relative risk ratio for autistic disorder was 0.92 while for another autism spectrum disorder it was 0.83. These results show that the incidence of autism was fairly similar for vaccinated and unvaccinated children. AKA, the MMR vaccine does NOT cause autism, so nothing to worry about! This analysis helps prove there is no relation and further debunked Wakefield’s study before it was entirely retracted in 2010. Go science!!