November 24, 2025. Assistance from Claude AI.
On November 19, 2025, the Centers for Disease Control and Prevention substantially revised its “Autism and Vaccines” webpage, replacing language stating that vaccines do not cause autism with text questioning whether that claim is “evidence-based.” The change has prompted an unprecedented wave of criticism from major medical organizations, scientific experts, current and former government health officials, and members of Congress.
What Changed on the CDC Website
The CDC’s vaccine safety webpage previously stated: “Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD).”
The revised page now opens with three key points:
- “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.”
- “HHS has launched a comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links.”
The headline “Vaccines do not cause Autism” remains on the page, but with an asterisk. A footnote explains: “The header ‘Vaccines do not cause autism’ has not been removed due to an agreement with the chair of the U.S. Senate Health, Education, Labor, and Pensions Committee that it would remain on the CDC website” (Centers for Disease Control and Prevention, 2025).
Health and Human Services Secretary Robert F. Kennedy Jr. told The New York Times in an interview published November 21 that he personally ordered the changes. “The whole thing about ‘vaccines have been tested and there’s been this determination made,’ is just a lie,” Kennedy stated (Stolberg, 2025).
Overwhelming Response from Medical and Scientific Community
The response from established medical and scientific institutions has been swift and uniformly critical.
Medical Organizations
American Academy of Pediatrics: “We are appalled to find that the content on the CDC webpage ‘Autism and Vaccines’ has been changed and distorted, and is now filled with anti-vaccine rhetoric and outright lies about vaccines and autism,” the organization stated. AAP President Dr. Susan Kressly added, “The conclusion is clear and unambiguous… 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” (Stobbe, 2025).
American Medical Association: Dr. Sandra Adamson Fryhofer, an AMA trustee, said the organization was “deeply concerned that perpetuating misleading claims on vaccines will lead to further confusion, distrust and ultimately, dangerous consequences for individuals and public health” (Stolberg, 2025).
Autism Science Foundation: The organization, which represents autism researchers and families, issued a statement saying: “We are appalled to find that the content on the CDC webpage ‘Autism and Vaccines’ has been changed and distorted, and is now filled with anti-vaccine rhetoric and outright lies about vaccines and autism” (Stobbe, 2025).
Autism Self Advocacy Network: “The CDC’s web page used to be about how vaccines do not cause autism. Yesterday, they changed it. It says that there is some proof that vaccines might cause autism. It says that people in charge of public health have been ignoring this proof. These are lies” (Allen, 2025).
Former CDC Officials
Dr. Mandy Cohen, CDC Director during the Biden administration, stated: “There is overwhelming evidence that vaccines do not cause autism but do save lives. [This] damages the C.D.C.’s credibility and risks endangering children by driving down vaccination rates and leaving kids vulnerable to preventable diseases like measles and whooping cough” (Stolberg, 2025).
Dr. Demetre Daskalakis, former CDC vaccine chief who resigned in August 2025, wrote on social media that “the weaponization of the voice of CDC is getting worse” and told The Washington Post that the “CDC cannot currently be trusted as a scientific voice,” accusing both the agency and Kennedy of “validating false claims” (Nevradakis, 2025).
Dr. Daniel Jernigan, former director of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, said at a November 19 news briefing that Kennedy has been “going from evidence-based decision-making to decision-based evidence making” (Stobbe, 2025).
Dr. Debra Houry, who was among CDC officials who resigned in August, said: “I spoke with several scientists at CDC yesterday and none were aware of this change in content. When scientists are cut out of scientific reviews, then inaccurate and ideologic information results” (Stobbe, 2025).
Leading Researchers
Dr. Amesh Adalja, Johns Hopkins Center for Health Security: Kennedy and his “nihilistic Dark Age compatriots have transformed the CDC into an organ of anti-vaccine propaganda” (Allen, 2025).
Dr. Atul Gawande, Brigham and Women’s Hospital: “The CDC website has been lobotomized” (Allen, 2025).
Dr. Paul Offit, Children’s Hospital of Philadelphia Vaccine Education Center: “Kennedy thinks he’s helping children with autism, but he’s doing the opposite” by drawing resources away from promising research leads (Allen, 2025).
Helen Tager-Flusberg, Boston University professor emerita who leads an advocacy group of more than 320 autism scientists: “They’re massaging the data, and the outcome is going to be, ‘We will show you that vaccines do cause autism’” (Allen, 2025).
Dr. Angela Rasmussen, University of Saskatchewan virologist and co-editor-in-chief of the journal Vaccine: “It will be cited as evidence, even though it’s completely invented” (Allen, 2025).
Congressional Response
On November 21, 80+ members of Congress, led by Rep. Kim Schrier, M.D. (D-WA), sent a letter to Secretary Kennedy stating: “The installation of false claims, without CDC expert career staff knowledge according to reporting, regarding a false connection between autism and vaccines is a direct threat to our nation’s public health” (Schrier et al., 2025).
The letter cited nine peer-reviewed studies from major journals showing no correlation between vaccines and autism, including:
- A 2015 JAMA study of 95,727 U.S. children finding no link between MMR vaccine and autism, even among children with older autistic siblings (Jain et al., 2015)
- A 2019 New England Journal of Medicine study of 657,461 Danish children finding no association (Hviid et al., 2019)
- Multiple studies on thimerosal (mercury preservative) finding no link (Madsen et al., 2003)
The letter concluded: “For a Health and Human Services Secretary who constantly talks about radical transparency, you have obscured real, evidence-based science and replaced it with conspiracy theories. You have discredited sound science vetted by scientists across the globe, undermined confidence in the CDC, and endangered Americans’ health” (Schrier et al., 2025).
Editorial Boards
The Wall Street Journal editorial board, in a piece titled “RFK Jr. Turns the CDC Against Vaccines,” wrote: “Under this logic, the fact that robust studies on childhood vaccines haven’t found an autism link means it can’t be ruled out. But you can’t disprove a negative” (Editorial Board, 2025).
What the Scientific Evidence Actually Shows
The scientific consensus on vaccines and autism is based on extensive research across multiple countries and populations.
Major Studies and Reviews
The Congressional letter and scientific experts point to multiple lines of evidence:
Institute of Medicine Reviews: The CDC webpage itself acknowledges a timeline of reviews:
- 1991: “No data were identified that address the question of a relation between vaccination with DPT or its pertussis component and autism”
- 2012: “The evidence is inadequate to accept or reject a causal relationship between diphtheria toxoid–, tetanus toxoid–, or acellular pertussis–containing vaccine and autism”
- 2014 and 2021 Agency for Healthcare Research and Quality reviews: “insufficient evidence” to support or reject a causal relationship remained unchanged (Centers for Disease Control and Prevention, 2025)
Critical distinction: These reviews stated the evidence was “inadequate to accept or reject” a link—not that evidence of a link had been found and ignored.
Large-Scale Epidemiological Studies:
- A 2019 study in The Lancet estimated that vaccines have averted 154 million deaths worldwide since 1974, including 146 million children under age 5 (Stolberg, 2025)
- A 2019 study of 600,000 children found no association between MMR vaccine and autism (Stolberg, 2025)
- A 2018 study following 82,000 pregnant women who received the tetanus, diphtheria and pertussis vaccine found their babies were not at increased risk for autism (Stolberg, 2025)
Meta-analyses: A 2014 meta-analysis reviewed case-control and cohort studies, concluding “vaccines are not associated with autism” (Schrier et al., 2025).
What Studies the New CDC Page References
The revised CDC webpage primarily cites:
- Studies from the 1990s and 2000s finding “insufficient evidence” to rule out a link (not evidence supporting a link)
- One observational study finding correlation between aluminum adjuvants in vaccines and autism prevalence
- One cross-sectional study finding “threefold risk” with early hepatitis B vaccination, which the Agency for Healthcare Research and Quality determined provided “insufficient evidence of an association”
The page does not cite recent studies showing no link, nor does it mention the life-saving benefits of vaccines.
The Aluminum Adjuvant Question
The CDC page highlights one study finding correlation between aluminum adjuvants in vaccines and rising autism rates. However:
- A 2025 Danish study of more than 1.2 million children found no link between aluminum in vaccines and autism (Editorial Board, 2025)
- Infants ingest significantly more aluminum from breast milk or formula during the first six months of life than they receive from vaccines (Editorial Board, 2025)
- As multiple scientists noted, correlation does not prove causation
Research Gaps vs. Evidence of Risk
Dr. Daniel Salmon of Johns Hopkins Bloomberg School of Public Health, a longtime advocate for vaccine safety research, acknowledged to The New York Times that Kennedy is correct that “high-quality large studies had not been conducted to examine a potential link between autism and other shots given in the first year of life,” specifically hepatitis B and the DTP combination shot.
However, Salmon emphasized that “the question of whether additional vaccine safety research is needed is separate from the question of whether children should be vaccinated” (Stolberg, 2025).
Dr. Paul Offit of Children’s Hospital of Philadelphia countered: “So what’s his hypothesis? What is it about the hepatitis B vaccine that he thinks causes autism?” No reputable scientists had made claims that would warrant investigations into these specific vaccines before Kennedy’s appointment (Stolberg, 2025).
The Political Context: Broken Promises?
The webpage changes have created political tensions, particularly with Sen. Bill Cassidy (R-LA), chair of the Senate Health, Education, Labor, and Pensions Committee.
The Cassidy Agreement
Before voting to confirm Kennedy as HHS Secretary, Sen. Cassidy—a physician—announced on the Senate floor in February 2025 that Kennedy had made several promises, including that “CDC will not remove statements on its website pointing out that vaccines do not cause autism” (Bailey, 2025).
Cassidy cast what was reportedly the tie-breaking vote for Kennedy’s confirmation based on these assurances.
The Asterisk Strategy
While the headline “Vaccines do not cause autism” technically remains on the CDC page, the body text contradicts it. Critics argue this is a lawyerly interpretation that keeps the letter of the promise while violating its spirit.
Cassidy’s Response
On November 21, Sen. Cassidy posted on X (formerly Twitter): “I’m a doctor who has seen people die from vaccine-preventable diseases. 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” (Allen, 2025).
However, Cassidy did not directly mention Kennedy by name in his statement. When approached by reporters at the Capitol before the website changes were public, Cassidy declined to answer questions about Kennedy’s Advisory Committee on Immunization Practices and abruptly ended the conversation (Allen, 2025).
According to Bailey (2025) writing in Reason, Kennedy has now broken every major promise made to Cassidy: he removed COVID vaccines from the recommended schedule for children and pregnant women, fired vaccine experts from the Advisory Committee on Immunization Practices and replaced them with vaccine skeptics, and effectively removed the “vaccines don’t cause autism” message from the CDC website (Bailey, 2025).
Who Made the Decision?
Multiple sources report that CDC scientists were not consulted about the changes. Former CDC official Dr. Debra Houry told reporters: “I spoke with several scientists at CDC yesterday and none were aware of this change in content” (Stobbe, 2025).
Abigail Tighe, executive director of the National Public Health Coalition (a group including current and former CDC and HHS staffers), confirmed that “the CDC’s developmental disability group was not asked for input on the changes” (Allen, 2025).
Kennedy told The New York Times that he personally ordered the website alterations. “It is highly unusual for a health secretary to personally order a change to scientific guidance,” the Times reported. “Former C.D.C. officials say that such changes are usually initiated by agency scientists, and in some cases might go to the secretary’s office for review” (Stolberg, 2025).
What Comes Next
The CDC webpage states that HHS is conducting a “comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links.” Kennedy has appointed David Geier, described by multiple sources as a longtime vaccine skeptic, to lead this assessment. Geier’s research with his late father Mark has been “widely repudiated” according to experts quoted in multiple outlets (Allen, 2025; Stobbe, 2025).
Kennedy’s Advisory Committee on Immunization Practices is scheduled to meet in December to discuss potential changes to childhood vaccine recommendations, including whether to maintain the recommendation for hepatitis B vaccine at birth (Allen, 2025).
Multiple scientists expressed concern that the website changes foreshadow broader attacks on childhood vaccination.
“This isn’t over,” said Helen Tager-Flusberg of Boston University, who leads an advocacy group of more than 320 autism scientists. “They’re massaging the data, and the outcome is going to be, ‘We will show you that vaccines do cause autism’” (Allen, 2025).
Public Health Implications
Health experts warn that undermining confidence in vaccines could have serious consequences.
Before modern vaccines:
- As many as 200,000 Americans contracted whooping cough annually, with about 9,000 deaths (Stolberg, 2025)
- Approximately 450 Americans died from measles each year before the vaccine became available in 1963 (Stolberg, 2025)
- Polio paralyzed thousands of children annually
Currently, whooping cough cases are surging in the United States as vaccination rates decline (Nevradakis, 2025).
Jessica Steier, a public health scientist specializing in science communications, reviewed the research in an August 2025 New York Times opinion piece, finding “more than 40 high-quality studies since 1998 involving over 5.6 million people across seven countries. All found no connection between vaccines and autism” (Stolberg, 2025).
Alison Singer, co-founder of the Autism Science Foundation and mother of an autistic adult, told KFF Health News: “If you’re a new mom and not aware of the last 30 years of research, you might say, ‘The government says we need to study whether vaccines cause autism. Maybe I’ll wait and not vaccinate until we know’” (Allen, 2025).
The Broader Context
The CDC website changes come amid what critics describe as a broader effort to question vaccine safety:
- In early November 2025, Kennedy announced that COVID-19 vaccines had been removed from the recommended immunization schedule for healthy children and pregnant women, making it harder for some expectant mothers to access the vaccines because insurance companies may be less likely to cover them (Bailey, 2025)
- Kennedy fired all vaccine experts from the CDC’s Advisory Committee on Immunization Practices and appointed vaccine skeptics in their place (Bailey, 2025)
- The CDC has lost approximately one-third of its staff in 2025, with entire divisions gutted and leadership fired or forced to resign (Allen, 2025)
Conclusion
The revision of the CDC’s autism and vaccines webpage represents a significant departure from decades of public health messaging based on extensive scientific research. The change has been met with unprecedented criticism from major medical organizations, hundreds of scientists, former government health officials, and members of Congress across the political spectrum.
While questions remain about specific research gaps—particularly regarding vaccines that have not been studied as extensively as MMR—the overwhelming scientific consensus based on studies of millions of children is that vaccines do not cause autism. The new CDC language characterizing this consensus as “not evidence-based” contradicts the position of every major medical and scientific organization.
The debate now centers on two questions: First, what level and type of evidence is sufficient to make public health recommendations? And second, who should have authority over the scientific guidance provided by federal health agencies—career scientists or political appointees?
As this situation continues to develop, parents and the public are left to navigate conflicting messages from federal health authorities, medical organizations, and scientific experts about one of the most consequential decisions they make for their children’s health.
References
Allen, A. (2025, November 21). What To Know About the CDC’s Baseless New Guidance on Autism. KFF Health News. https://kffhealthnews.org/news/article/cdc-autism-baseless-new-guidance-website
Bailey, R. (2025, November 22). RFK Jr. Breaks His Promises About the CDC on Vaccines and Autism. Reason. https://reason.com/2025/11/22/rfk-jr-breaks-his-promises-about-the-cdc-on-vaccines-and-autism/
Centers for Disease Control and Prevention. (2025, November 19). Autism and Vaccines. https://www.cdc.gov/vaccine-safety/about/autism.html
Editorial Board. (2025, November 24). RFK Jr. Turns the CDC Against Vaccines. The Wall Street Journal. https://www.wsj.com/opinion/rfk-jr-cdc-vaccines-autism-website
Hviid, A., Vinsløv Hansen, J., Frisch, M., & Melbye, M. (2019). Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study. Annals of Internal Medicine, 170(8), 513-520. https://doi.org/10.7326/M18-2101
Jain, A., Marshall, J., Buikema, A., Bancroft, T., Kelly, J. P., & Newschaffer, C. J. (2015). Autism Occurrence by MMR Vaccine Status Among US Children With Older Siblings With and Without Autism. JAMA, 313(15), 1534-1540. https://jamanetwork.com/journals/jama/fullarticle/2275444
Madsen, K. M., Lauritsen, M. B., Pedersen, C. B., Thorsen, P., Plesner, A. M., Andersen, P. H., & Mortensen, P. B. (2003). Thimerosal and the Occurrence of Autism: Negative Ecological Evidence From Danish Population-Based Data. Pediatrics, 112(3), 604-606. https://doi.org/10.1542/peds.112.3.604
Nevradakis, M. (2025, November 20). ‘Honesty at Last’: CDC Says ‘No Evidence’ to Support Claim that Vaccines Don’t Cause Autism. The Defender. https://childrenshealthdefense.org/defender/cdc-autism-webpage-no-evidence-support-claim-vaccines-do-not-cause-autism
Schrier, K., et al. (2025, November 21). Letter to Secretary Robert F. Kennedy Jr. [Congressional letter]. U.S. House of Representatives.
Stobbe, M. (2025, November 20). CDC website is changed to raise suspicions of a vaccines-autism link. AP News. https://apnews.com/article/cdc-autism-vaccines-7b1890f626dd5921fafd00fdd1e6425a
Stolberg, S. G. (2025, November 21). RFK Jr. Says He Instructed CDC to Change Vaccines and Autism Language on Website. The New York Times. https://www.nytimes.com/2025/11/21/us/politics/rfk-jr-cdc-vaccines-autism-website.html
This analysis is based on review of primary source documents including the CDC webpage itself, congressional correspondence, peer-reviewed studies, and reporting from multiple news organizations. Readers are encouraged to consult original sources to form their own conclusions.