And for all those people who have anecdotal stories remember that the correlation may seem remarkable to you because anomalies always seem remarkable when they happen to you. However, what you need to understand is that in the context of the 306 million people in the United States, anomalies are actually not only expected, it would be remarkable if they didn't occur. Here's a back of the envelope explanation why (from another blogger that frequents BA http://padraic2112.wordpress.com/2009/04/25/my-last-vaccination-post-for-a-while/):

 

There is a simple reason why this is not relevant, take the following facts:

* children take vaccines

* autism displays its first symptoms in childhood

* children under the age of 5 make up ~7% of the population

* there are ~306 million people in the U.S.

* about 80% of children are vaccinated entirely

 

This means 306 x 0.07 x .8 = 1.7 million children (roughly) have been vaccinated. With the vaccination schedule being what it is, then, there are somewhere around 100,000 children getting a shot every month (that last one is hand-wavey, it assumes a lot about frequency distributions, but that's not really germane to my point). Autism rates are estimated at anywhere between 1 in 100 and 1 in 150 children, that means we have about 17,000 diagnosis of autism. If every single one of those autism diagnosis was given to a vaccinated child (they're not, but again for our sake here it introduces very small error), and those 17,000 have a scatter distribution of vaccination patterns, that means not one, not dozens, not hundreds, but *thousands* of those diagnosis came within days or weeks of a vaccination: yes, this means that dozens will occur within an hour of a vaccination.

 

Put those thousands of people together on a message board (and since autism is hard to deal with, a very high percentage of these family *do* bond together, like SMA sufferers or MS or cancer or any other family-impacting disease), you'll have a few thousand people all saying to each other, "Gee... MY kid got a shot right before her symptoms started showing, too! There are thousands of us! THAT CAN'T BE A COINCIDENCE."

 

But you can see, it actually *isn't* a coincidence... it's exactly what we would EXPECT to happen.