Verdict: FALSE. The claim that vaccines may cause autism is not supported by scientific evidence.
In November 2025, the CDC—under HHS Secretary RFK Jr.—rewrote its vaccine-autism webpage to suggest the science is unsettled. It is not. Over 1.2 million children studied across 10+ meta-analyses show no link. The original 1998 study was retracted as fraud. Autism diagnosis increases correlate with improved detection, not vaccination rates. This is one of the most thoroughly debunked claims in medical history.
In November 2025, the Centers for Disease Control and Prevention (CDC) modified its "Autism and Vaccines" webpage under direction from HHS Secretary Robert F. Kennedy Jr. The new language states that "vaccines do not cause autism" is "not an evidence-based claim" and that "studies have not ruled out" a vaccine-autism connection. [1]
This represents a stark reversal from decades of scientific consensus established by peer-reviewed research involving over 1.2 million children across multiple countries. [2] [3]
This report examines the CDC changes, traces the origin of the vaccine-autism myth to Andrew Wakefield's retracted and fraudulent 1998 paper, and evaluates the scientific evidence accumulated over 25 years. The conclusion is clear: vaccines do not cause autism.
I. What the CDC Changed
On November 18, 2025, the CDC's "Autism and Vaccines" webpage underwent significant revisions. The changes were made at the direction of political appointees within HHS, reportedly without input from CDC scientists. [11] [31]
Previous Language (Pre-November 2025):
"No links have been found between any vaccine ingredients and autism spectrum disorder."
New Language (November 2025):
"The claim 'vaccines do not cause autism' is not an evidence-based claim... Scientific studies have not ruled out the possibility that infant vaccines contribute to the development of autism."
HHS Secretary RFK Jr. publicly confirmed he directed these changes. [12] In a September 2025 press conference alongside President Trump, Kennedy had stated his department would identify the cause of the "autism epidemic" and accused parents who vaccinate their children without "doing their own research" of being responsible for their children's autism. [13] [14]
The Washington Post reported that the CDC has been ordered to conduct a new study into potential vaccine-autism connections, despite overwhelming existing evidence against such a link. [15]
II. The Scientific Consensus
The claim that vaccines cause autism is one of the most thoroughly investigated hypotheses in medical history. The conclusion across decades of research is unequivocal: there is no causal link.
Key Studies
Taylor et al. 2014 Meta-Analysis: Combined data from 5 cohort studies (1,266,327 children) and 5 case-control studies (9,920 children). Found no relationship between vaccination and autism or ASD. [2]
Hviid et al. 2019 (Denmark): Followed 657,461 children born 1999-2010. Found no increased risk of autism in vaccinated vs. unvaccinated children, including among children with autistic siblings or other risk factors. [3] [34]
Jain et al. 2015 (JAMA): Studied 95,727 children, including 1,929 with older siblings with ASD. Found no harmful association between MMR vaccine and ASD even in genetically susceptible children. [18]
Demicheli et al. 2012 (Cochrane Review): Systematic review of MMR vaccine safety. Concluded no evidence of a link to autism, Crohn's disease, or other conditions. [19]
Institutional Consensus
Every major medical and public health organization has concluded there is no vaccine-autism link:
| Study | Year | Sample Size | Finding |
|---|---|---|---|
| Madsen et al. (Denmark) | 2002 | 537,303 | No association |
| Smeeth et al. (UK) | 2004 | 5,308 cases | No association |
| Demicheli (Cochrane) | 2012 | 14.7M doses | No association |
| Taylor et al. (Meta) | 2014 | 1,266,327 | No association |
| Jain et al. (JAMA) | 2015 | 95,727 | No association |
| Hviid et al. (Denmark) | 2019 | 657,461 | No association |
III. Origin of the Myth: The Wakefield Fraud
The vaccine-autism myth originated with a single 1998 paper by British physician Andrew Wakefield and 12 co-authors, published in The Lancet. The paper claimed to find a link between the MMR vaccine, bowel disease, and autism in 12 children. [4]
The Fraud Exposed
Investigative journalist Brian Deer, writing for the BMJ, exposed systematic fraud in the study:
- Data falsification: Results were changed from "unremarkable" to "nonspecific colitis" [21]
- Patient selection: Children were not "consecutively referred" but specifically recruited through anti-vaccine networks [21]
- Fabricated timeline: A 14-day link between vaccination and symptom onset was invented [21]
- Undisclosed conflicts: Wakefield received £435,643 from lawyers planning lawsuits against vaccine manufacturers [4]
- Patent conflict: Wakefield held a patent for a rival single measles vaccine [4]
Consequences
February 2010: The Lancet fully retracted the paper. [5] [23]
May 2010: The UK General Medical Council found Wakefield guilty of "serious professional misconduct" and struck him from the medical register. [22]
2011: The BMJ published a series declaring the paper "an elaborate fraud". [21]
Despite this, Wakefield relocated to the United States and continues to promote anti-vaccine views. His influence was cited in measles outbreaks in the UK, where MMR vaccination rates dropped below 80% in parts of England following his paper's publication.
IV. Why the Myth Persists
Despite overwhelming evidence, the vaccine-autism myth has proven remarkably resilient. Several factors contribute to its persistence:
Correlation vs. Causation
Autism symptoms often become apparent around 12-18 months of age—the same period when children receive the MMR vaccine. This temporal coincidence creates an intuitive but false perception of causation. [9] [30]
Increased Autism Diagnosis ≠ Increased Autism
Autism prevalence has risen from 1 in 150 (2000) to 1 in 31 (2022). [26] [27] However, this increase is attributed to:
- Broader diagnostic criteria (DSM-5 changes)
- Improved awareness and screening
- Earlier diagnosis
- Better access to services, especially in minority communities
Social Media Amplification
Anti-vaccine content spreads faster than corrections on social media platforms. A 2020 study found vaccine misinformation posts receive 4x more engagement than factual content.
Emotional Appeal
Parents seeking explanations for their child's autism are vulnerable to narratives offering a specific cause. The vaccine explanation provides a target for blame and a sense of control that "genetic predisposition" does not.
Political Amplification
The appointment of RFK Jr.—a longtime vaccine skeptic—as HHS Secretary has given unprecedented government platform to debunked claims. Critics, including members of Kennedy's own family, have called his views "dangerous." [33]
V. Legal Resolution: The Omnibus Autism Proceeding
The U.S. Vaccine Court (Court of Federal Claims) conducted the Omnibus Autism Proceeding from 2002-2010, the largest and most comprehensive legal evaluation of the vaccine-autism claim. [28]
Special Masters reviewed 5,400 claims and heard testimony from dozens of expert witnesses. The court selected three test cases representing the strongest evidence for causation.
The Verdict
All three test cases were rejected. Special Master George Hastings wrote:
"The petitioners' theory of vaccine-related causation is scientifically unsupportable... The weight of scientific research and evidence does not support the petitioners' contentions."
Appeals were denied. The court found that the evidence presented by petitioners was based on "speculation rather than sound science."
VI. Final Verdict
✅ The Evidence
- 10+ major studies involving over 1.2 million children
- Zero studies in peer-reviewed literature finding a causal link
- Wakefield paper retracted for fraud, author struck off medical register
- Vaccine Court ruled against causation in 5,400 cases
- Every major medical institution confirms no link
❌ The CDC's New Language
The revised CDC webpage language—stating that science "has not ruled out" a vaccine-autism link—employs a rhetorical trick. Science cannot prove a negative absolutely. By this logic, one could claim science "has not ruled out" that eating bread causes autism.
The CDC's previous language accurately reflected the scientific consensus. The new language is misleading and was inserted by political appointees, not scientists.
⚠️ Public Health Risk
Declining vaccination rates have real consequences. Measles—a disease that was eliminated in the US in 2000—has seen recurring outbreaks linked to unvaccinated communities. In 2019, 1,282 measles cases were reported in the US, the highest since 1992.
The claim that vaccines cause autism is FALSE.
This is one of the most thoroughly studied questions in medical science. The evidence is overwhelming: vaccines do not cause autism. The original study claiming a link was retracted as fraudulent, its author was banned from practicing medicine, and subsequent research involving millions of children has consistently found no association.
The CDC's November 2025 webpage changes do not reflect new scientific evidence—they reflect political interference in public health communication. The scientific consensus remains unchanged: vaccines are safe, effective, and do not cause autism.