Controversial preprint revives vaccine–autism debate, draws sharp pushback from medical experts

A new and controversial scientific review claiming a link between aluminum-containing vaccine adjuvants and autism spectrum disorder (ASD) has reignited a long-running and deeply polarizing debate within public health and medical research circles.

The review, led by Brian Hooker, Chief Scientific Officer of the advocacy group Children’s Health Defense (CHD), analyzed more than 200 previously published studies and argues that aluminum adjuvants used in some vaccines may trigger autismsSD in what the authors describe as “genetically susceptible” children.

The paper was posted on January 31, 2026, to Zenodo, an open-access preprint server, and has not yet undergone peer review.

According to the authors, the reviewed studies — spanning immunology, neuropathology, toxicology, genetics, and epidemiology — collectively suggest that aluminum nanoparticles could provoke immune responses that lead to neuroinflammation during early brain development.

They contend that this inflammation could disrupt synaptic pruning, a normal neurological process that occurs primarily between infancy and early childhood.

Hooker described the paper as “groundbreaking,” stating that it offers a mechanistic explanation for a causal relationship between vaccines and autism — a claim that has been repeatedly rejected by major health authorities over the past three decades.

Several co-authors echoed the view. Christopher Shaw, a neuroscientist and professor at the University of British Columbia, said he hopes the findings will prompt the U.S. Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) to reconsider the use of aluminum adjuvants, particularly in pediatric vaccines.

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Aluminum adjuvants are currently used in a number of vaccines recommended by the CDC, including those for hepatitis B, DTaP, Haemophilus influenzae type b (Hib), pneumococcal disease, hepatitis A, and human papillomavirus (HPV).

However, the publication has been met with strong skepticism from the broader medical and scientific community, which maintains that decades of large-scale epidemiological studies involving millions of children worldwide have found no credible evidence linking vaccines or vaccine ingredients to autism.

Medical experts note that Zenodo hosts preliminary research and does not vet submissions for scientific accuracy. They also stress that preprint papers often change substantially — or are rejected outright — during formal peer review.

In December 2025, the journal Pediatrics, published by the American Academy of Pediatrics (AAP), reaffirmed its position that aluminum adjuvants are safe at the levels used in vaccines.

That publication prompted CHD to file a federal lawsuit against the AAP in January, alleging conflicts of interest and misleading public statements — claims the AAP has not conceded.

Public health agencies, including the CDC, World Health Organization (WHO), and National Institutes of Health (NIH), continue to state that autism is a complex neurodevelopmental condition with strong genetic underpinnings, and that vaccines remain one of the most rigorously studied medical interventions in history.

Health experts warn that renewed vaccine-autism narratives — even when framed as emerging science — can undermine public confidence in immunization programs and increase the risk of outbreaks of preventable diseases.

As the debate continues, researchers and clinicians emphasize the need for rigorous peer review, transparent data analysis, and careful public communication when addressing issues with significant implications for child health and public safety.