McCullough Foundation report names childhood vaccination the leading modifiable autism risk factor
Why it matters
This is the most comprehensive synthesis the reform movement has produced, and its lead author, epidemiologist Nicolas Hulscher, sits at the center of the expert testimony now reaching Congress and state legislatures.
The McCullough Foundation report, titled “Determinants of Autism Spectrum Disorder” and published in October 2025, characterizes combination and early-timed routine childhood vaccination as the most significant modifiable risk factor for autism.
The report states that of 136 studies examined, 107 suggest a link between vaccination and autism, while 29 found no association. It calls for a full reassessment of the U.S. childhood vaccine schedule, citing what its authors describe as a lack of long-term safety studies on the cumulative impact of the full pediatric schedule.
Critics note the report is not peer-reviewed, was published in an open repository, and includes research that mainstream reviewers have disputed; major scientific organizations continue to conclude that vaccines do not cause autism. It is a solid starting point for anyone who wants to go to the underlying studies directly.
Source
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The record behind the witness: Hulscher's 39 studies and why legislators keep calling him
Nicolas Hulscher has become the reform movement's most-requested expert witness, appearing before both the U.S. Senate and the Michigan House inside a single year. Behind those appearances is a specific, checkable body of published work, and readers deserve to see what it actually consists of rather than take the label 'epidemiologist' on faith.