Study: Receipt of Multiple Childhood Vaccines ‘Most Dominant Modifiable Risk Factor’ for Autism

A recent meta-analysis report from the McCullough Foundation has identified routine childhood vaccination as the “most dominant modifiable risk factor” for autism spectrum disorder (ASD). Drawing from more than 300 peer-reviewed studies, the analysis compared risk factors contributing to the drastic spike in autism and found one clear factor that stood out as the most significant driver: receipt of multiple vaccines during. The peer reviewed open-access report, entitled Determinants of Autism Spectrum Disorder, was published on Oct. 27, 2025, and has been archived on the open-access online repository Zenodo.¹

Of 136 studies examining childhood vaccines or their excipients (inactive ingredients within the vaccine formula), 29 of the studies found neutral risks or no association, while 107 of the studies inferred a possible link between vaccination and development of ASD or other neurodevelopmental disorders. Twelve studies, which compared routinely vaccinated children with completely unvaccinated children or young adults, consistently demonstrated that children who remained unvaccinated had superior overall health . This included significantly lower risks of chronic poor health conditions and neuropsychiatric disorders. Of the studies that came to a “neutral” conclusion, it is significant to note that there was an absence of a genuine unvaccinated control group.¹

“Virtually every child receives a battery of vaccines, and the number increases every year,” said the lead author of the report, Peter McCullough, MD, MPH in an interview with Emmy award–winning investigative reporter Grant Stinchfield. “What we saw were these patterns, which appear to be post-vaccination patterns. It’s not just autism—it’s ADHD, it’s seizures, and tics. This, to me, looks like a post-encephalitic pattern of brain inflammation after vaccines. It’s no specific vaccine or vaccine ingredient, but it’s the sum total effect in a susceptible child. And it is modifiable because we can modify the vaccines that are given.”²

Tylenol vs. Vaccines: Clarifying the Leading Risk Factor

The report comes just weeks after the U.S. Department of Health and Human Services (DHHS), in coordination with the White House, announced that acetaminophen (Tylenol) (which many pregnant women and children routinely receive before or after vaccination) is a potential environmental risk factor for autism. While Dr. McCullough acknowledges that Tylenol is a possible contributor, he clarifies that vaccination—not acetaminophen—emerged as the most dominant risk factor in the McCullough Foundation’s report.³

“Vaccines aren’t the only possible cause,” McCullough explained. “In the Swedish study that examined Tylenol, only about 7.5 percent of pregnant women reported using it. [Vaccination] is really the common factor.”² The researchers point to growing biological and population-level evidence suggesting that giving multiple vaccines close together—especially early in infancy—may contribute to neuroimmune dysfunction and developmental regression in susceptible children.¹

While mainstream media outlets and public health authorities continue to assert that the vaccine–autism link has been long debunked by numerous studies, the report’s authors note that nearly all studies that found no association between vaccines and autism lacked a truly unvaccinated control group and were limited by misclassification, confounding, or insufficient verification of vaccination status.¹

McCullough Credits Andrew Wakefield With Giving an Early Warning

In his interview with Stinchfield, McCullough credited Andrew Wakefield, MD, whose research in the late 1990’s linking vaccination and neurodevelopmental disorders made him a controversial figure within the medical community, with warning about a possible association between MMR vaccine and autism. “I give credit to Andrew Wakefield, who is one of the authors [of the report]. He made the seminal observation in 1998 and published it in The Lancet,” McCullough noted.²

Wakefield and the 10 co-authors of the 1997 Lancet report clearly stated that the findings “did not prove an association” but called for further investigation of autism in relation to the MMR (measles, mumps, rubella) vaccine. The report did not cause a major public controversy until 2004 after thousands of parents filed petitions on behalf of their vaccine injured children in the federal Vaccine Injury Compensation Program created under the National Childhood Vaccine Injury Act of 1986. The vaccine-related autism cases were bundled into a class action type lawsuit against DHHS and adjudicated in the U.S. Court of Federal Claims alleging that mercury and measles containing vaccines administered in early childhood had caused their children to regress into autism.¹

In February 2004, a British newspaper journalist published a report alleging that Wakefield had undisclosed financial interests in MMR vaccine injury lawsuits and had engaged in unethical methods conducting the research for the Lancet paper, calling the conclusions of the study into question. The allegations against Wakefield were believed to have been part of a larger campaign to discredit the potential link between regressive autism and vaccination.¹

Wakefield’s findings were widely rejected by the medical establishment and mainstream media and ultimately led to the British Medical Council removing his medical license in 2009, sparking a decades-long public smear campaign that framed him and his work as fraudulent. Yet now, more than 25 years later—long after The Lancet retracted the Wakefield-led study—the McCullough Foundation’s independent analysis revisits the same scientific questions and reaches strikingly similar conclusions.⁴

McCullough said in his interview with Stinchfield that subsequent studies have continued to reinforce Wakefield’s early observations. During the exchange, Stinchfield noted the intensity of the public health messaging around vaccination, saying, “All we’ve been told is if you don’t give your kids vaccines, they’re going to die! This is just not the case, doc.”²

“The Institute of Medicine considered it a closed case in 2004,” McCullough shared, “and since then, we now have 12 studies showing that children who remain unvaccinated are healthier and free of these problems, including autism, if they take no vaccines at all.”²

The Science is Not “Settled

The World Council for Health, an international coalition of health initiatives focused on human rights and medical ethics, reacted to the McCullough Foundation’s findings and shared an interview with McCullough on its Substack platform. “We’re told the science is settled. The debate is closed. But what if new science demands that we reopen it?” the organization wrote.

“The last major investigation into a potential vaccine–autism link was carried out in 2004, and autism numbers have continued to climb every year since.” Their publication, which ranks among the Top 50 Health Politics Substacks, says of the first-of-its-kind report that “their findings are stark, and their recommendations could, and should, send shockwaves through the public health establishment.”⁵

Interviewed by Tess Lawrie, MBBCh, PhD and Dr. Christof Plothe, DO, McCullough elaborated on the study’s findings: “The most significant finding was the strength of the association. We observed a clear and statistically significant signal that a specific vaccine-related exposure was substantially more prevalent in the autism cases than in the neurotypical controls.”⁵

McCullough added:

The most surprising aspect was the magnitude of the effect—it was not a small, borderline finding. This is precisely the kind of signal that should have prompted immediate and rigorous investigation by our public health agencies years ago.⁵

Parents Called for Independent Scientific Research Into the Childhood Vaccine Schedule in the 1990s

In 2013, the National Academy of Sciences Institute of Medicine (IOM) published the report The Childhood Immunization Schedule and Safety: Stakeholder Concerns, Scientific Evidence and Future Studies. That report revealed there were significant gaps in scientific knowledge about vaccine safety, with fewer than 40 scientific studies published in the previous decade which specifically addressed the federally recommended early childhood vaccine schedule (birth to age six).⁶

So, more than a decade ago, the IOM concluded that there is not enough scientific evidence to determine if the recommended early childhood schedule is or is not associated with the development of a number of brain and immune system disorders prevalent among children today, including:

• Asthma
• Atopy
• Allergy
• Autoimmunity
• Autism
• Learning Disorders
• Communication Disorders
• Developmental Disorders
• Intellectual Disability
• Attention Deficit Disorder
• Disruptive Behavior Disorder
• Tics and Tourette’s Syndrome
• Seizures
• Febrile Seizures
• Epilepsy

After the IOM report was released in 2013, NVIC co-founder and president Barbara Loe Fisher pointed out that for the previous two decades, parents of vaccine injured children had been publicly calling for bench science investigating the biological mechanisms for vaccine injury and death and the evaluation and comparison of long-term health outcomes for vaccinated and unvaccinated children.^{7 8}

Fisher disagreed with the IOM’s recommendation that future studies of the safety of the childhood vaccine schedule should be conducted by DHHS and its corporate partners using closed databases such as the Vaccine Safety Datalink (VSD). She said:

Replication is the gold standard in science because it prevents fraud in science. Transparency is important to public trust in science. It is a conflict of interest for federal agencies, which are developing and patenting new vaccines, regulating, making policy for and promoting mandating of vaccines, to also be in charge of conducting research into the safety of federal vaccine policies. Using closed patient databases, such as the VSD, prevents independent replication of vaccine safety conclusions made by DHHS officials collaborating with HMO’s and pharmaceutical corporations in public-private partnerships.⁹

Defending the informed consent ethic for the past four decades,  on Aug. 27, 2025 NVIC called for an end to mandatory vaccination laws vaccine in the U.S.^{10 11}

McCullough Foundation Calls for Greater Transparency

The McCullough Foundation’s researchers are calling for greater transparency and a comprehensive investigation into cumulative vaccine safety. “The United States is in the vaccine business,” McCullough said in his Stinchfield interview. “They haven’t been forthright on bringing forward a comprehensive report on the autism epidemic.” As the report notes, “No study has ever evaluated the cumulative safety of the full pediatric vaccine schedule for neurodevelopmental outcomes through childhood or adolescence,” a gap the authors describe as a critical failure in public health research.^{1 2}

“We really need to have an overhaul of the vaccine schedule, move toward risk stratification, and eliminate liability protections on vaccines,” McCullough said. “The companies [need to] take them off the market very quickly, and then we need to remove these requirements for school, military, and employment.”²

Physicians Sue CDC for Lack of Safety Studies for Childhood Vaccine Schedule

In August 2025, a lawsuit was filed by two physicians against the U.S. Centers for Disease Control and Prevention (CDC) for recommending the childhood vaccine schedule without proof of safety for the more than 70 doses received by age 18. The lawsuit requests that the schedule be revised until CDC officials can provide adequate evidence that the schedule is safe. The Plaintiffs, Paul Thomas, MD and Kenneth Stoller, MD request that the childhood schedule be placed under category B which requires “shared decision making” between provider and patient, as opposed to categorized as CDC recommended.¹²

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