The Independent: Italian court rules MMR vaccine did trigger autism

[Ms. Toad]

87. "thimerosal was totally removed from all childhood vaccines in 2001"

is inaccurate statement, offered to shut down discussion. I'll give you that it isn't a fact

The only reason to assert that thimerosal is no longer in vaccines is to tell the speaker that, on the really, really, really, off chance that there is something to their theory, the "cause" isn't present any more. End of discussion. Except that it isn't true.

I have never personally argued that thimerosal causes anything - my beef is with stating things which are inaccurate to shut down discussion (or stating the "fact" carelessly, and then digging in when the "fact" is proven false - as happened the last time I pointed out that some childhood vaccines do still contain thimerosal).

But for the sake of discussion - you are correct that correlation does not equal causation. It is, however, one of the standard starting points for scientific inquiry. Not everyone who expresses a concern about a correlation is mistaking it for causation - but may be instead be suggesting that a particular correlation should be further explored to see if causation can be established. And not all correlations are first noticed by the scientific community. I noticed a correlation between my daughter's poultry consumption and her disease activity, and because the correlation was very strong became pretty convinced of a particular disease pathway (genetic predisposition + environmental trigger). Several years after I was convinced, the national support group for disease adopted that explanation for the disease pathway. (I'm not claiming to have had anything to do with their change - just noting that a correlation I (as a lay person) observed in a one person "study" is now accepted as causation.)

The fact that no study has established a link between autism and vaccination does not necessarily mean there is no link. GWAS studies are in their infancy (but progressing very quickly). One of the things these studies are establishing is that many diseases once thought to be homogeneous are actually heterogeneous - at times nearly custom diseases even though the manifestation is similar enough that up until now they have been thought to be a single uniform disease. I don't know if that is where autism is trending - but I do know that these disease variations are now theorized to be the cause failures of multiple drug trials for my daughter's illness. Results which looked extremely promising turned out not only to be not promising, but actually harmful - in part because the population being studied was thought to all have the same disease so the results of the small study would be scalable to a larger study (or at least not dramatically different). Because there was a different disease variation mixture in the smaller group studies than in the ones they scaled to, the results were not as predicted - they were in fact the opposite of what the smaller study predicted and at least one trial was halted because it was deemed to be unethical to continue. What is now being done, though, is to go back to those smaller group studies and to type the disease by variant to see if there is a smaller population for whom the drugs actually are useful (rather than harmful).

So, in the case of autism, where similar GWAS studies are being undertaken, we may find similar things. The studies which have been unable to establish a link autism and vaccination are equivalent to the larger drug trials done on my daughter's disease - and are almost certainly applicable to the population of people with autism as a whole, but there may well be variants of autism which are too small to make a statistically significant difference in the large population studies. And, just like my daughter's illness, we may well need to return to this question to look at subgroups of people with autism to see whether, in populations with a particular disease variation, vaccination (or something in it, like the adjuvants most vaccines contain) is the (or one of the) environmental triggers for manifestation of autism.

I don't think that means you toss vaccinations out of the window - but I do think autism is one of many diseases, most of them immune related, which may have environmental triggers, which suggest that we rethink the balance between rote vaccination for everyone and (until exome sequencing is readily available and cheap enough to be worth the investment) systematic screening for indicators of special susceptibility - as well as taking a look at our overall scheme to see whether a different implementation would strike a better balance between societal needs and the likelihood of risk to vulnerable populations (based on what we are now learning about how autoimmune disorders work).