Vaccines do not cause autism!

The entire universe in blog form
May 12 2008 9:51 AM

Vaccines do not cause autism!

I just can't make this any clearer. Vaccines do not cause autism. Study after study has shown this, in multiple ways. The removal of the MMR (mumps-measles-rubella) vaccine in Japan did not lead to a decline in the number of cases of autisms diagnosed; instead the number of children falling in the autism spectrum increased.

A study in Denmark (link goes to Science Magazine; subscription required) showed the same thing: long after thimerosal-based vaccines were discontinued, autism-related diagnoses continued to rise:

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Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death from the Skies! Follow him on Twitter.

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Now the first big epidemiological studies weigh in. One comes from Denmark, which eliminated thimerosal from childhood vaccines in 1992. A team led by Kreesten Madsen of the Danish Epidemiology Science Centre in Aarhus reasoned that if thimerosal were a major cause of autism, incidence of new cases should drop once it was removed. In the September issue of the journal Pediatrics, they report that, instead of declining, the incidence continued to skyrocket after 1992.

They supply a graph:


This graph is a clincher. If they were related in any way, you'd see a decline. Instead it continues to rise. Note that the little dip we see at the end is many many years after thimerosal was stopped; if it were related to autism then the dip would have started years earlier.

The obvious conclusion is that vaccines containing thimerosal have nothing or at best extremely little to do with autism (and note that the MMR vaccine never contained thimerosal!). An obvious hypothesis explaining the continuing rise of cases diagnosed is that we are getting better at identifying it, and/or that the use of the term autism spectrum includes more symptoms that were previously not considered to be related.

This has not stopped the antivaccination people from marching on, however. The Washington Post is reporting that two cases trying to establish a link are being brought to court today. The article says

To win, the attorneys for the two boys, William Mead and Jordan King, will have to show that it's more likely than not that the vaccine actually caused the injury.

This makes me very unhappy. A judge is not necessarily suited to decide medical science! If it were a case of medical ethics or negligence, or something along those lines, then certainly the judiciary system should be involved, but this is a clear-cut case of scientifically established reality. Vaccines do not cause autism.

As always in situations as delicate as these, let me say that I am a parent, and I love my daughter very much. If she had been diagnosed with some sort of issue like autism, I know I would have been devastated. I also know it is human nature to try to find a cause, some place to lay blame. But sometimes there is no blame.

I also know it's human nature to take anything that happens after a given event and blame that event for it. I gave my daughter a vaccine, then she turned up with autistic symptoms. Therefore...

But life isn't always like that. And I very much hope that the judges in this case are familiar with the term post hoc, ergo propter hoc: after this, therefore because of this. It's a classic logical fallacy, and the antivax contingent is riding it right into the judicial system.

And there is a chilling side to this. Vaccines are among the greatest achievements in human history. This is not hyperbole. Millions upon millions of lives have been saved by vaccines. Smallpox is gone. Polio is gone. A vaccine has been developed to prevent HPV, saving millions of women from the horrors of cervical cancer.

If vaccinations decline, then we will see an increase in mumps, measles, rubella, whooping cough (pertussis), and many more terrible afflictions... problems that are ultimately completely curable. This is stone, cold fact. Worse, these problems are far more severe in children.

So let me make this as clear as I possibly can:

The antivaccination movement purports to try to save children. Instead, if it is successful it may be condemning millions of them to terrible ailments, and a significant fraction of them to death.

It is that simple.

Hat tip to John Keller for sending me the link to the WaPo article.