The CDC webpage makes claims about the relationship between vaccines and autism spectrum disorder. The original version of this page stated that vaccines do not cause autism. However, as of November 19, 2025, the page was modified to claim that the statement “vaccines do not cause autism” is “not an evidence-based claim” and that “studies have not ruled out the possibility that infant vaccines cause autism.” This is an evaluation.
Research assistance from Claude AI.
Summary
The original CDC content stating vaccines do not cause autism was accurate and supported by extensive scientific evidence. The new content added on November 19, 2025, contradicts decades of peer-reviewed research involving millions of children. The scientific consensus, supported by meta-analyses of studies involving over 1.2 million children, confirms no causal link exists between vaccines and autism.
Accuracy and Truthfulness
The Original CDC Content (Pre-November 19, 2025)
The original version of this page was scientifically accurate. Its claim that studies have shown no link between vaccines and autism is strongly supported by the scientific literature. A comprehensive 2014 meta-analysis by Taylor, Swerdfeger, and Eslick examined five cohort studies involving 1,256,407 children and five case-control studies involving 9,920 children and found no relationship between vaccination and autism (Taylor et al., 2014). The cohort data showed an odds ratio of 0.99 for autism (95% confidence interval 0.92-1.06), meaning vaccinated and unvaccinated children had virtually identical autism rates. The same meta-analysis found no relationship between autism and MMR vaccines (odds ratio 0.84), thimerosal (odds ratio 1.00), or mercury (odds ratio 1.00).
Additional research has consistently replicated these findings. A landmark Danish study of 537,303 children found no statistically significant difference in autism rates between MMR-vaccinated and unvaccinated children, and no association between the age at vaccination, time since vaccination, or date of vaccination and autism development (Madsen et al., 2002). A 2012 Cochrane review examined 5 randomized controlled trials, 1 controlled clinical trial, 27 cohort studies, 17 case-control studies, 5 time-series studies, 1 case cross-over trial, 2 ecological studies, and 6 self-controlled case series studies and found no qualitative evidence of an association between MMR vaccine and autism (Demicheli et al., 2012).
The Institute of Medicine (now National Academy of Medicine) conducted a thorough 2004 review and concluded that the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism (Institute of Medicine, 2004).
The New Content (Added November 19, 2025)
The revised webpage contains several claims that contradict the scientific evidence.
The claim that the statement “vaccines do not cause autism” is not evidence-based is false. The Autism Science Foundation stated in response to the changes that “the science is clear that vaccines do not cause autism” and that “no environmental factor has been better studied as a potential cause of autism than vaccines” (Autism Science Foundation, as cited in CNN, 2025). Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, called the new statement “confusing by design” (NPR, 2025).
The revised page claims that “studies supporting a link have been ignored by health authorities.” This is misleading. Studies purporting to show a connection between vaccines and autism have been examined and found to be fraudulent or methodologically flawed. The most notable example is the 1998 Wakefield study, which was retracted by The Lancet and found to be based on scientific misconduct with misrepresented data (Children’s Hospital of Philadelphia, 2024). No credible, methodologically sound studies have established a causal link.
The new content suggests that correlation between rising autism rates and increased vaccine schedules merits study of a causal link. However, correlation does not establish causation. Autism diagnoses have increased due to expanded diagnostic criteria, increased awareness, and improved screening, not changes in actual prevalence caused by vaccines.
Logical Fallacies Identified
The revised CDC content contains several logical fallacies:
False Cause (Post Hoc Ergo Propter Hoc): The suggestion that rising autism rates correlating with increased vaccine schedules indicates a possible causal relationship commits the false cause fallacy. Many factors have changed since the 1980s, including diagnostic criteria, awareness, and access to healthcare. Correlation between two trends does not establish that one causes the other.
Shifting the Burden of Proof: The claim that “studies have not ruled out the possibility” reverses the scientific burden of proof. In science, when a hypothesis has been repeatedly tested and found unsupported (as the vaccine-autism hypothesis has been), the burden shifts to those claiming a link to provide positive evidence, not to others to “rule out” every conceivable possibility.
Appeal to Ignorance: Arguing that something might be true because it hasn’t been absolutely disproven is a logical fallacy. Science cannot prove a universal negative, but the overwhelming preponderance of evidence shows no causal relationship.
Cherry-Picking: The revised content selectively highlights studies or statistical correlations that might suggest uncertainty while ignoring the vast body of research demonstrating no link. Citing a single cross-sectional study about hepatitis B vaccines while ignoring multiple large-scale cohort studies and meta-analyses constitutes selective use of evidence.
Misuse of Irony
The revised page invokes the Data Quality Act to justify removing evidence-based content. The Data Quality Act requires federal agencies to ensure quality, objectivity, utility, and integrity of information. Using this law to justify adding content that contradicts the preponderance of scientific evidence is an ironic misapplication of a statute designed to ensure accuracy.
Lack of Self-Awareness
The revised content criticizes the previous CDC position as not being “evidence-based” while simultaneously promoting claims that lack support from the body of peer-reviewed scientific literature. This demonstrates a significant lack of self-awareness, as the new content fails to meet the very standard it claims to uphold.
Additionally, the page states that career scientists at CDC were not consulted about the changes and were “caught off guard” (Axios, 2025), indicating that the revisions bypassed normal scientific review processes at the agency responsible for disease prevention.
Overgeneralization
The new content suggests that because autism “is likely to be multi-factorial,” vaccines cannot be ruled out as a contributing cause. This represents faulty logic. The fact that a condition has multiple causes does not mean any particular hypothesized cause is valid, especially when that specific cause has been extensively studied and rejected by the evidence.
Conspiratorial Thinking and Conspiracy Theories
The revised CDC content echoes longstanding conspiracy theories about vaccines and autism that have circulated since the late 1990s following the fraudulent Wakefield study. Key elements of conspiratorial thinking evident in the new content include:
Claims of Cover-Up: The assertion that “studies supporting a link have been ignored by health authorities” implies a deliberate suppression of evidence by scientific and medical institutions. This is a hallmark of conspiracy theories, which posit that powerful institutions conceal the truth.
Distrust of Mainstream Scientific Consensus: Despite overwhelming evidence from independent researchers across multiple countries, the revised content suggests that the scientific consensus is somehow compromised or incomplete.
Pattern-Seeking in Correlation: Citing the correlation between vaccine schedules and autism prevalence as potentially meaningful reflects the tendency in conspiratorial thinking to perceive meaningful patterns in coincidental data.
The changes to the CDC website came under the leadership of Health and Human Services Secretary Robert F. Kennedy Jr., who has a documented history of promoting vaccine skepticism and the debunked vaccine-autism link (CNN, 2025; NPR, 2025; Axios, 2025).
References
Axios. (2025, November 20). CDC just changed its website to promote RFK Jr.’s debunked vaccine-autism link. https://www.axios.com/2025/11/20/cdc-website-rfk-vaccines-autism
Centers for Disease Control and Prevention. (2025). Autism and vaccines. U.S. Department of Health and Human Services. https://www.cdc.gov/vaccine-safety/about/autism.html
Children’s Hospital of Philadelphia. (2024). Vaccines and autism. Vaccine Education Center. https://www.chop.edu/vaccine-education-center/vaccine-safety/vaccines-and-other-conditions/autism
CNN. (2025, November 20). CDC website changed to include false claims that link autism and vaccines. https://www.cnn.com/2025/11/20/health/cdc-website-autism-vaccines
Demicheli, V., Rivetti, A., Debalini, M. G., & Di Pietrantonj, C. (2012). Vaccines for measles, mumps and rubella in children. Cochrane Database of Systematic Reviews, 2012(2), CD004407. https://doi.org/10.1002/14651858.CD004407.pub3
DeStefano, F., Price, C. S., & Weintraub, E. S. (2013). Increasing exposure to antibody-stimulating proteins and polysaccharides in vaccines is not associated with risk of autism. The Journal of Pediatrics, 163(2), 561-567. https://doi.org/10.1016/j.jpeds.2013.02.001
Institute of Medicine. (2004). Immunization safety review: Vaccines and autism. National Academies Press. https://doi.org/10.17226/10997
Institute of Medicine. (2012). Adverse effects of vaccines: Evidence and causality. National Academies Press. https://doi.org/10.17226/13164
Madsen, K. M., Hviid, A., Vestergaard, M., Schendel, D., Wohlfahrt, J., Thorsen, P., Olsen, J., & Melbye, M. (2002). A population-based study of measles, mumps, and rubella vaccination and autism. New England Journal of Medicine, 347(19), 1477-1482. https://doi.org/10.1056/NEJMoa021134
NPR. (2025, November 20). The CDC revives debunked ‘link’ between childhood vaccines and autism. https://www.npr.org/sections/shots-health-news/2025/11/20/nx-s1-5199024/cdc-autism-vaccines-rfk-health
Taylor, L. E., Swerdfeger, A. L., & Eslick, G. D. (2014). Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine, 32(29), 3623-3629. https://doi.org/10.1016/j.vaccine.2014.04.085