CHD Scientists Dispel 23-Year-Old Study Debunking MMR Vaccine’s Link to Autism

Press Release
For Immediate Release
August 1, 2025

Children’s Health Defense (CHD) Chief Scientific Officer Brian Hooker, Ph.D. and Senior Research Scientist Karl Jablonowski, Ph.D. published an editorial today, “Unadjusted Analysis of a Population-Based Study of Measles, Mumps, and Rubella Vaccination and Autism,” in Integrative Medicine: A Clinician’s Journal.

The two scientists reanalyzed Madsen et al. (2002), a Danish study involving 537,303 children and the cornerstone publication that claims vaccines don’t cause autism. Madsen et al.’s unadjusted results do not support rejecting the causal link between the MMR vaccine and autism. The strongly worded paper lacks strong data to support its claims. There is adjustment inversion, where the signal switches from the vaccine favoring harm to favoring protection against autistic disorder upon statistical adjustment. The authors of the original research paper are unclear about the number of vaccinated and unvaccinated children with autism in their study.

Madsen et al. claim that the “study provides strong evidence against the hypothesis that MMR vaccination causes autism” and that the “power of the study is reflected in the narrow 95 percent confidence intervals.” However, the confidence intervals are notably quite large. The original authors are 95% confident that children are anywhere from 47% less likely to 24% more likely to develop autistic disorder due to the MMR vaccine. This is “strong evidence” of the need for more evidence.

“The original Madsen paper is foundational to the pharmaceutical industry canard that ‘vaccines don’t cause autism,” said Brian Hooker, Ph.D., chief scientific officer, Children’s Health Defense. “However, the numbers literally don’t add up and based on this and myriad other issues with this foundation, the question of vaccines and autism desperately needs to be put back on the table.”

The CHD scientists criticize the authors of Madsen et al. for not revealing their statistical model or data in light of the statistical adjustment inversion. The raw data shows the MMR vaccine was harmful, while the adjusted data shows the MMR vaccine was beneficial. Accepting their analysis is a matter of faith, not science.

“A landmark publication in one of the most prestigious medical journals in the world (whose erroneous conclusions are reverberated through news outlets and doctors’ offices alike for the last 23 years) is shown to be invalid by the most basic form of arithmetic,” said Karl Jablonowski, Ph.D., senior research scientist, Children’s Health Defense. “The problem is not that we were sold $69 billion a year in vaccines based on faulty analyses that riddled our children with toxins and left them with chronic and debilitating diseases, if not death.  The problem is that we bought it.”

Madsen et al. have cohort confusion in their study. The number of vaccinated versus unvaccinated individuals for both autistic disorder and other autism spectrum disorders differs between Table 1 and Table 2. This discrepancy significantly affects the interpretation of the results. CHD scientists interpret from Table 1 unadjusted data, with 90% confidence that children who receive an MMR vaccination have an 18% greater incidence of autistic disorder or other autism spectrum disorders.

The Danish study utilized one of the few data sources that collected population-wide autism screening and immunization at a time when other theorized toxic exposures were minimal. It is imperative that the quarter-century-old data set be made available to independent researchers.

Children’s Health Defense® is a 501(c)(3) non-profit organization. Our mission is ending childhood health epidemics by eliminating toxic exposure. We will restore and protect the health of children by eliminating environmental exposures, holding responsible parties accountable, and establishing safeguards to prevent future harm of children’s health. Protecting Children. Exposing Harms. Seeking Justice.

For more information or to donate to CHD, visit ChildrensHealthDefense.org.