Analysis of Studies

Jain A, et al. (2015) Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. JAMA 313(15):1534–1540. )

  • This was a retrospective cohort study of a commercial health plan’s administrative claims database.
  • It did not compare fully non-vaccinated to vaccinated siblings. Only MMR vaccination was studied.
  • Many factors confound findings, including “healthy user bias.”
  • Younger siblings may be less likely to be fully vaccinated compared to older siblings if older siblings regressed into autism after vaccination.
  • Individuals who are not genetically or environmentally predisposed to vaccine injury will have far lower rates of reported injury even with higher rates of vaccination. And those with a history of neurological, developmental, or health issues may have higher rates of injury even with lower rates of vaccination.
  • The MMR is not the only vaccine with adverse reactions (such as encephalitis) that can lead to a diagnosis of autism.
  • Studies such as this one do not reveal vulnerable populations nor prove one way or another the impact of vaccination on autism rates among susceptible populations.
  • Negative results of association at the population level do not rule out causality for any individual or susceptible subgroups.

Australian meta review, Luke E. Taylor, et al., Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies., 32 VACCINE 3623(2014).”

  • The author of this meta-review sorted through the entire body of published work on the relationship between vaccines and autism, just as the IOM did in 2012, and found just 10 studies that met his parameters.
  • Five of these studies (Andrews, Hviid, Madsen, Verstraeten, Price) were analyzed in another review published the same year and found, as the review title states, “Methodological Issues and Evidence of Malfeasance in Research Purporting to Show Thimerosal in Vaccines Is Safe.
  • In regards to the Hviid study, in 2004, the IOM Adverse Event report, “The committee identified a few limitations of the study, including its time-series design and the generalizability of the study’s findings to the U.S. situation, especially with regard to the different dosing schedule used in Denmark and the relative genetic homogeneity of the Danish population.”
  • Per the Verstraeten study, IOM found, “Limitations include the study’s ability to answer whether thimerosal in vaccines causes autism because the study tests a dose-response gradient, not exposure versus non-exposure.”
  • Per the Madsen study, IOM found, “However, despite the reanalysis the authors stated that autism incidence after 1995 may have been exaggerated due to the change in including outpatient cases into the Danish Psychiatric Central Register. This limits the study’s contribution to causality.” And in their 2012 Report, IOM noted, “One of the authors of this article, P. Thorsen, was indicted for embezzlement on April 13, 2011. The implications for the integrity of the study are unknown at this time”
  • Also in IOMs 2012 report, “DeStefano et al., 2004; Richler et al., 2006; Schultz et al., 2008; Taylor et al., 2002; Uchiyama et al., 2007) had very serious methodological limitations that precluded their inclusion in this assessment [IOMs 2012 report]. Taylor et al. (2002) inadequately described the data analysis used to compare autism compounded by serious bowel problems or regression (cases) with autism free of such problems (controls). DeStefano et al. (2004) and Uchiyama et al. (2007) did not provide sufficient data on whether autism onset or diagnosis preceded or followed MMR vaccination.”
  • William Thompson, one of the researchers on the DeStefano et al study, mentioned above, came forward in 2014 as a whistleblower on this study, stating results that did, in fact show a causal link between the timing of the administration of the MMR and autism were removed prior to presentation of the results to the IOM.
  • IOM in 2012 determined per the Mrozek-Budzyn et al., “This study was rated as having serious limitations because it did not provide information on medical conditions among the controls and relied on medical record abstraction for immunization dates and autism diagnosis dates.”
  • The Uno et al study was far too under-powered (Cases n=189 were diagnosed with ASD, controls n=224) for a condition that effects 1-2% of the population and that has a diffuse genetic risk. The IOM found that the population also lacked genetic population diversity.
  • Smeeth et al. is also too under-powered to provide a useful conclusion, and we refer you to this published criticism: