Has the CDC Quietly Changed Its Stance on Vaccines and Autism?
On November 19–20, 2025, the U.S. Centers for Disease Control and Prevention (CDC) made a significant and abrupt revision to its public-facing guidance on the relationship between vaccines and autism. This change, which replaced longstanding language unequivocally stating that vaccines do not cause autism with a more equivocal assertion that “the claim ‘vaccines do not cause autism’ is not an evidence-based claim,” has ignited widespread controversy and concern among public health experts, medical organizations, policymakers, and the general public.
The CDC’s November 2025 Webpage Update – What Changed?
The New Language
On November 19, 2025, the CDC’s “Autism and Vaccines” webpage was revised to state: “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.” The page further asserts that “studies supporting a link have been ignored by health authorities,” and that the CDC and other agencies have historically promoted the “no link” position to prevent vaccine hesitancy.
A prominent subheading, “Vaccines do not cause Autism,” remains at the top of the page, but now carries an asterisk. A footnote explains that this phrase was retained due to an agreement with Senator Bill Cassidy (R-La.), chair of the Senate Health, Education, Labor, and Pensions Committee, who had secured a pledge from Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. not to remove the statement as a condition for Cassidy’s support of Kennedy’s nomination.
Comparison to Previous CDC Position
Prior to this update, the CDC’s language was clear and direct: “Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD). No links have been found between any vaccine ingredients and ASD. Vaccines do not cause autism”. The CDC cited multiple large-scale studies, systematic reviews, and meta-analyses, including its own 2013 research, to support this position. The agency also provided detailed explanations debunking concerns about specific vaccine ingredients such as thimerosal and aluminum, and referenced the consensus of the National Academy of Medicine and other leading scientific bodies.
The new language, by contrast, emphasizes scientific uncertainty, highlights studies that purportedly support a link (while claiming they have been ignored), and questions the strength of existing evidence by noting the absence of randomized controlled trials (RCTs) and the reliance on observational studies.
Official Explanations and Internal Process
When queried by journalists, HHS Communications Director Andrew Nixon described the revision as a “common-sense update that brings CDC’s website in line with our commitment to transparency and gold standard science,” reiterating that the update was part of a broader effort to ensure all public-facing information reflects “ongoing scientific inquiry”.
However, multiple reports from reputable news outlets (including The Washington Post, STAT, CBS News, and NPR) indicate that the change was orchestrated by political appointees at HHS, with no input from CDC career scientists or subject matter experts. Former and current CDC officials have stated they were blindsided by the update and did not participate in its creation or vetting.
Timeline of CDC Positions on Vaccines and Autism
Early 2000s to 2024: Affirming No Link
From the late 1990s through 2024, the CDC consistently maintained that there was no credible evidence linking vaccines to autism. This position was rooted in a robust body of scientific research, including:
- Large cohort and case-control studies in the U.S., Denmark, Finland, Japan, and other countries, all finding no association between the MMR (measles, mumps, rubella) vaccine or thimerosal-containing vaccines and autism.
- Systematic reviews and meta-analyses, such as the 2014 meta-analysis by Taylor et al., which pooled data from over 1.2 million children and found no increased risk of autism associated with vaccination.
- Statements from the National Academy of Medicine (formerly the Institute of Medicine), the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Food and Drug Administration (FDA), all affirming that vaccines do not cause autism.
The CDC’s website and public communications reflected this consensus, emphasizing the safety and importance of childhood immunization.
November 2025: Abrupt Shift
The November 2025 update marks a dramatic departure from this longstanding position. The new language introduces doubt, suggests that the absence of RCTs means causality cannot be ruled out, and references studies that have been widely discredited or found to be methodologically weak.
Timeline Table: CDC Language on Vaccines and Autism
| Date/Period | CDC Position/Website Language |
| 2004–2024 | “Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder.” |
| “No links have been found between any vaccine ingredients and ASD.” | |
| “Vaccines do not cause autism.” | |
| Nov 19–20, 2025 | “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.” |
| “Studies supporting a link have been ignored by health authorities.” | |
| “Vaccines do not cause Autism*” (with asterisk and footnote referencing agreement with Sen. Cassidy) |
The table above illustrates the stark contrast between the CDC’s previous unequivocal language and the new, more ambiguous and skeptical framing.
Scientific Evidence on Vaccines and Autism
Major Studies and Meta-Analyses
A vast body of scientific literature has investigated the alleged link between vaccines and autism, consistently finding no causal association:
- Taylor et al. (2014) Meta-Analysis: Reviewed case-control and cohort studies involving over 1.2 million children, concluding there is no association between vaccination and autism.
- Hviid et al. (2019, 2025): Large Danish cohort studies found no increased risk of autism in children who received the MMR vaccine or vaccines containing aluminum adjuvants.
- DeStefano et al. (2013, CDC): Examined antigen exposure from vaccines in the first two years of life and found no difference in autism rates between vaccinated and unvaccinated children.
- Cochrane Reviews (2021): Systematic reviews of MMR and other childhood vaccines found no evidence of increased autism risk.
These studies have been conducted in multiple countries, using diverse methodologies, and have been replicated over decades.
Methodological Considerations: Observational Studies vs. RCTs
The CDC’s revised webpage criticizes the reliance on observational studies, arguing that only RCTs can “prove” causation or its absence. However, leading epidemiologists and methodologists emphasize that:
- RCTs are not always ethical or feasible: Withholding vaccines from children to conduct an RCT would expose them to preventable diseases and is considered unethical.
- Observational studies, when well-designed, provide robust evidence: Large cohort and case-control studies, especially when replicated across populations and adjusted for confounders, can reliably detect or rule out associations.
- Hill’s Criteria for Causality: Epidemiologists use a set of criteria (strength, consistency, temporality, plausibility, etc.) to assess causality in the absence of RCTs. The vaccine-autism hypothesis fails these criteria.
As Dr. Paul Offit and Dr. David Mandell have noted, it is impossible to “prove a negative” in science; instead, causality is assessed by the weight and consistency of evidence.
Discredited and Cherry-Picked Studies
The CDC’s new webpage references studies that have been widely discredited or found to be methodologically weak, such as:
- Andrew Wakefield’s 1998 Lancet Study: This study, which first suggested a link between MMR and autism, was retracted for fraud and ethical violations. Subsequent investigations found no evidence supporting its claims.
- Ecological Studies on Aluminum: The CDC now cites a 2014 ecological study linking aluminum in vaccines to autism, despite stronger individual-level studies (e.g., Hviid et al., 2025) finding no such association. Experts warn that ecological studies are the weakest form of epidemiological evidence and are prone to confounding and spurious correlations.
The CDC’s selective citation of such studies, while ignoring the overwhelming body of contrary evidence, has been criticized by scientists as misleading and scientifically unsound.
Reactions from Public Health Experts, Medical Organizations, and Former CDC Officials
Medical and Scientific Organizations
The CDC’s revision has been met with near-universal condemnation from leading medical and scientific organizations:
- American Academy of Pediatrics (AAP): President Dr. Susan J. Kressly stated, “Since 1998, independent researchers across seven countries have conducted more than 40 high-quality studies involving over 5.6 million people. The conclusion is clear and unambiguous: There’s no link between vaccines and autism. Anyone repeating this harmful myth is misinformed or intentionally trying to mislead parents. We call on the CDC to stop wasting government resources to amplify false claims that sow doubt in one of the best tools we have to keep children healthy and thriving: routine immunizations”.
- World Health Organization (WHO): Reiterated that “a robust, extensive evidence base exists showing childhood vaccines do not cause autism. Large, high-quality studies from many countries have all reached the same conclusion. Original studies suggesting a link were flawed and have been discredited”.
- Autism Science Foundation: Called the new CDC language “misinformation” that “actually contradicts the best available science,” and warned that it will “sow confusion and fear and ultimately lead to more serious illnesses and deaths among vulnerable children”.
- American Medical Association (AMA): Trustee Dr. Sandra Adamson Fryhofer emphasized that “extensive and rigorous studies consistently show that vaccines are safe. Despite recent changes to the CDC website, an abundance of evidence from decades of scientific studies shows no link between vaccines and autism”.
Former and Current CDC Officials
Numerous former CDC leaders and current staff have expressed alarm and dismay:
- Dr. Demetre Daskalakis, former head of the CDC’s National Center for Immunization and Respiratory Diseases, called the changes a “public health emergency” and warned, “The weaponization of the voice of CDC is getting worse. CDC has been updated to cause chaos without scientific basis. DO NOT TRUST THIS AGENCY”.
- Dr. Debra Houry, former CDC chief science and medical officer, stated, “When scientists are cut out of scientific reviews, then inaccurate and ideologic information results. The CDC should be a data-driven agency based on science and not ideology, but when you take the scientists out of the process you get rhetoric that can harm families”.
- Dr. Daniel Jernigan, former CDC official, described the update as “going from evidence-based decision making to decision-based evidence making”.
- Dr. Fiona Havers, former CDC vaccine policy leader, said, “CDC scientists have been sidelined completely. RFK Jr. is abusing his position as HHS Secretary and is now using CDC as a platform to spread anti-vaccine propaganda”.
Current CDC staff, speaking anonymously, have described the update as a “glaring red flag” and “anti-science,” and have warned that the agency’s vaccine information is no longer credible.
Political and Policy Context
The change has been linked to the leadership of HHS Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, and to political negotiations involving Senator Bill Cassidy. Cassidy, a physician and chair of the Senate HELP Committee, had secured a promise from Kennedy not to remove the “vaccines do not cause autism” statement as a condition for supporting his nomination. Cassidy has since expressed strong disapproval of the website change, stating, “What parents need to hear right now is vaccines for measles, polio, hepatitis B and other childhood diseases are safe and effective and will not cause autism. Any statement to the contrary is wrong, irresponsible, and actively makes Americans sicker”.
Media Coverage and Investigative Reporting
The CDC’s update has been widely covered by major news outlets, including Reuters, AP, The New York Times, Washington Post, PBS, ABC, CBS News, NPR, STAT, Axios, CNBC, and others. The consensus among these reports is that:
- The change was made without scientific justification or new evidence.
- The update was orchestrated by political appointees at HHS, not by CDC scientists.
- The revision contradicts decades of scientific research and the consensus of the global medical community.
- The move has been celebrated by anti-vaccine groups and condemned by mainstream medical organizations and public health experts.
- The change is likely to undermine public trust in the CDC and in vaccines, and may contribute to declining vaccination rates and increased outbreaks of preventable diseases.
Motivations and Policy Context
HHS Leadership and Political Influence
The revision is widely attributed to the influence of HHS Secretary Robert F. Kennedy Jr., who has a long history of promoting vaccine-autism claims and skepticism toward established vaccine safety science. The change aligns with Kennedy’s public statements and policy agenda, including efforts to “revisit” the scientific consensus on vaccine safety and to launch new investigations into the causes of autism.
The update also reflects broader political dynamics, including negotiations with Senator Cassidy and the replacement of CDC leadership and advisory committees with Kennedy’s appointees, some of whom have anti-vaccine views.
Policy and Regulatory Implications
The CDC’s new language may have significant legal and regulatory consequences, including:
- Vaccine Injury Compensation: By casting doubt on the safety of vaccines, the CDC may open the door to more claims in the National Vaccine Injury Compensation Program, potentially threatening the viability of the program and the willingness of manufacturers to supply vaccines.
- State and Local Policy: Some states have already begun to distance themselves from CDC recommendations, forming independent alliances or issuing their own vaccine guidance in response to perceived federal politicization.
- Research Funding: The update coincides with reports of canceled or redirected research funding for autism genetics and vaccine safety studies, raising concerns about the politicization of research priorities.
Implications for Public Trust, Vaccine Uptake, and Misinformation
Public Trust in the CDC and Vaccine Information
Recent surveys show that public trust in the CDC and other government health agencies has declined sharply since the COVID-19 pandemic, with only about 57% of Americans now trusting the CDC for reliable vaccine information, down from over 80% in 2020. The CDC’s abrupt reversal on vaccines and autism is likely to further erode this trust, especially among parents, healthcare providers, and communities already skeptical of vaccines.
As Dr. Mandy Cohen, former CDC director, warned, “This change to CDC language undermines the agency’s scientific integrity, damaging its credibility on vaccines and other health recommendations. Most concerning, it risks endangering children by driving down vaccination rates and leaving kids vulnerable to preventable diseases like measles and whooping cough”.
Vaccine Uptake and Disease Outbreaks
The United States is already experiencing declining childhood vaccination rates and resurgences of vaccine-preventable diseases such as measles and pertussis. Weakening the CDC’s clarity on vaccine safety may accelerate these trends, leading to more outbreaks and preventable illness and death.
Misinformation Dynamics
The CDC’s new language has been celebrated by anti-vaccine groups, including Children’s Health Defense (formerly led by Kennedy), and is being used to legitimize and amplify vaccine-autism claims on social media and in public discourse. Experts warn that the change will be exploited to sow confusion, fear, and vaccine hesitancy, undermining decades of progress in public health communication and immunization.
Scientific Integrity and the Role of Federal Agencies
The CDC has long been regarded as a gold standard for scientific guidance on public health. The politicization of its communications, the sidelining of career scientists, and the adoption of language that contradicts the scientific consensus threaten the agency’s integrity and its ability to fulfill its mission.
Comparison with Other National and International Public Health Agencies
While the CDC has revised its language, other major health agencies – including the WHO, FDA, and public health agencies in Europe, Canada, and Australia – continue to affirm that vaccines do not cause autism, citing the same body of evidence that underpinned the CDC’s previous position. The divergence between the CDC and its global counterparts may create confusion for healthcare providers and the public, and may undermine international efforts to combat vaccine misinformation.
Legal, Regulatory, and Funding Consequences
The CDC’s new stance may have far-reaching legal and regulatory implications:
- Vaccine Mandates and School Entry Requirements: States may reconsider vaccine mandates for school entry if the federal government no longer unequivocally supports vaccine safety.
- Vaccine Injury Litigation: Plaintiffs may cite the CDC’s new language in lawsuits, potentially increasing liability for vaccine manufacturers and threatening vaccine supply.
- Research Funding: Reports of canceled or redirected funding for autism genetics and vaccine safety research raise concerns about the politicization of scientific priorities and the potential chilling effect on independent research.
- Congressional Oversight: Lawmakers from both parties have called for oversight hearings and investigations into the process and rationale behind the CDC’s update, and into the broader politicization of federal health agencies.
Expert Scientific Commentary and Op-Eds
Numerous experts have published commentaries and op-eds analyzing the CDC’s change:
- Dr. Paul Offit: Criticized the update as “taking advantage of a technicality of the scientific method,” and warned that “overwhelming evidence shows no link between vaccines and autism. Scientists can’t ever prove a negative”.
- Dr. David Mandell: Described the CDC’s new position as “the equivalent of ‘you haven’t proven that ghosts don’t exist’,” and emphasized that the burden of proof in science is not to prove a negative, but to assess the weight of evidence.
- Dr. Susan Kressly (AAP): Called the change “false information” and urged the CDC to “stop wasting government resources to amplify false claims that sow doubt in one of the best tools we have to keep children healthy and thriving: routine immunizations”.
- Autism Science Foundation: Stated, “No environmental factor has been better studied as a potential cause of autism than vaccines. The new statement shows a lack of understanding of the term ‘evidence’”.
Synthesis and Analysis
Has the CDC Quietly Changed Its Stance?
Yes. The CDC has, for the first time in decades, retreated from its unequivocal position that vaccines do not cause autism. The new language introduces doubt, elevates fringe or discredited studies, and undermines the scientific consensus. This change was made without input from CDC scientists, under political pressure, and in the absence of new scientific evidence.
Why Is This Shift Significant?
- Scientific Integrity: The CDC’s reversal undermines the principle that public health guidance should be based on the best available evidence, not political ideology or pressure.
- Public Trust: The change is likely to further erode trust in the CDC and in vaccines, at a time when vaccine hesitancy and misinformation are already on the rise.
- Vaccine Uptake: By casting doubt on vaccine safety, the CDC risks fueling declines in vaccination rates and triggering outbreaks of preventable diseases.
- Misinformation: The update provides ammunition for anti-vaccine activists and groups, legitimizing their claims and making it harder for healthcare providers and public health officials to counter misinformation.
- Legal and Policy Consequences: The new stance may have downstream effects on vaccine mandates, injury compensation, research funding, and regulatory policy.
The Broader Context
The CDC’s change must be understood in the context of broader political and cultural dynamics, including the politicization of science, the erosion of trust in institutions, and the rise of misinformation. The agency’s retreat from evidence-based guidance is both a symptom and a driver of these trends.
Key Statements from Major Organizations
| Organization | Statement on Vaccines and Autism (Nov 2025) |
| American Academy of Pediatrics | “The conclusion is clear and unambiguous: There’s no link between vaccines and autism. Anyone repeating this harmful myth is misinformed or intentionally trying to mislead parents.” |
| World Health Organization | “A robust, extensive evidence base exists showing childhood vaccines do not cause autism. Large, high-quality studies from many countries have all reached the same conclusion.” |
| Autism Science Foundation | “No environmental factor has been better studied as a potential cause of autism than vaccines. The new statement shows a lack of understanding of the term ‘evidence’.” |
| American Medical Association | “Extensive and rigorous studies consistently show that vaccines are safe. Despite recent changes to the CDC website, an abundance of evidence from decades of scientific studies shows no link between vaccines and autism.” |
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