Confounding By Contraindication and Exposure Dilution Bias in Vaccine Studies

It has come to my attention that my extensive article on this subject has started to get shared considerably. I was not planning on that just yet and am surprised anyone knows this site even exists…This post is to notify you that I have taken down the article and redirected it here, because I have decided to first publish this analysis in a peer-reviewed journal before discussing online. The main facet of the paper is a sensitivity analysis that looks at how wrong the results of MMR-autism studies are likely to be on account of their failure to address two systematic flaws called:

  1. Confounding by contraindication (the term healthy user bias is a little inaccurate)
  2. Exposure dilution bias.

Just one of several types of confounding by contraindication is depicted in the image at the top of this post. Exposure dilution bias in a nutshell is pictured below:

exposure dilution bias

You get the picture…These two flaws are  ignored in the vast majority of existing vaccine safety studies. The scant studies that do address these flaws turn up with results that say vaccines are dangerous. A seriously look needs to be taken by the research community to determine if inadequate appreciation for these two sources of bias and confounding are what explain such conflicting results.

In my analysis I greatly enrich a parameterized expression developed by Fine and Chen in 19921. Whereas their expression models the effect of confounding by contraindication, my expression simultaneously models both confounding by contraindication and exposure dilution bias. I am able to illustrate with plausible parameter values that the results of MMR-autism studies could be quite wrong and do not constitute reliable evidence of safety. Or at least I think so.

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1.
Fine P, Chen R. Confounding in studies of adverse reactions to vaccines. Am J Epidemiol. 1992;136(2):121-135. [PubMed]
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