The MMR vaccine and autism – what’s all that about? Part II

Even as Andrew Wakefield was drumming up public fear of the MMR vaccine, the medical community moved to disavow knowledge of a link between the MMR vaccine and the subesquent development of autism. They held the view that any relationship was merely temporal, i.e, the age at which most children get their MMR shot is the same age at which parents first notice signs of autism in children, and implored parents to get the shot for their children. But as Winston Churchill said, “A lie gets halfway around the world before the truth has a chance to get its pants on.”. The public’s (and even some doctors’) confidence in the vaccine was eroded, with the expected results.

So teams of medical researchers worldwide set out to prove what they already knew: that the MMR vaccine was not a cause of autism.

One of the most convincing studies done at the time was a Danish study by Madsen et al involved a cohort of all children born in Denmark 1991-8 (all 500,000+ of them!), of whom 82% were vaccinated for MMR. When comparing the vaccinated children with the unvaccinated, it was found that there was no significant difference between the autism rates between the two groups. Other studies various countries also reflected changes in autism rates that were not correlated to the amount of vaccine coverage.

A British study also found that parents of autistic children who were diagnosed after the Wakefield paper came out were more likely to connect their children’s autism with their MMR shot, as oppoed to parents of children diagnosed before the controversy (shocking, isn’t it?).

This research induced the Institute of Medicine (IOM) to state in 2004:

The committee concludes that the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism.

But even more data kept on streaming in, further strengthening the IOM’s conclusions:

Japan provided a natural experiment, when the MMR vaccine was withdrawn due to a defective mumps strain, and replaced with single shots so that no child received MMR after 1993. Autism rates continued to rise throughout – due to improved surveillance and broadened diagnostic criteria. This provided what was probably the largest nail in the coffin of the MMR-autism controversy.

And of course, the almost-obligatory Cochrane review also found no connection between MMR and either autism or bowel disease.

To be sure, Wakefield and his die-hard cronies were still not convinced. More recently, thimerosal, a mercury compound that used to be found in many inactivated vaccines (but never in MMR, which is a live virus), was blamed for the so-called “autism epidemic”. That hypothesis, too, is an interesting story and has a large body of research that led to its rejection by the IOM in the report quoted above. I’ll be discussing it in another (or another couple of) blog posts sometime in the future.

Other links for further research and reading:

http://www.mmrthefacts.nhs.uk/

Spiked Magazine’s articles on the MMR/autism controversy – A large series of articles by Dr. Michael Fitzpatrick, London GP and father of an autistic child. Fitzpatrick also wrote a book on the subject for worried parents.

http://www.neurodiversity.com/mmr.html – a large grab bag of studies, blog posts and opinion pieces on the subject.

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