More on thimerosal...

With a headline sure to amaze those who don't read the full story, the MetroWest Daily News (part of the Boston Herald family) proclaims, "Study links autism, vaccine." If this were even the least bit true, one suspects the MetroWest Daily News wouldn't be the only media outlet covering the story.

Rather, the story here is in reference to a paper published in the Journal of American Physicians and Surgeons titled "Early Downward Trends in Neurodevelopmental Disorders Following Removal of Thimerosal-Containing Vaccines."

The story explains:

"Autism diagnoses have dropped nationwide since mercury was removed from most childhood vaccines, according to a new study that some say lends credence to charges that vaccinations were responsible for a huge increase in autism cases. "

The paper in questions uses state and federal databases that track autism prevalance as well as VAERS, the Vaccine Adverse Event Reporting System. All of these sources have significant data reliability concerns, which, to the newspaper's credit, are noted in the story.

For example, adverse events can be reported to VAERS by anyone and are not verified for accuracy. This paper in Pediatrics (subscription required) -- Goodman, M.J., and Nordin, J. "Vaccine Adverse Event Reporting Source: A Possible Source of Bias in Longitudinal Studies." Feb. 2006; 117: 387-390 -- finds that most thimerosal-related reports to VAERS were directly related to pending litigation. The authors specifically warn researchers attempting to use VAERS data for studies such as the one above about the serious questions regarding its reliability.