The Vaccine Intelligence Report: Nov. 26 Special Edition – Vaccines & Autism

The Vaccine Intelligence Report—brought to you by Vaccinate Your Family—provides clear, fact-based updates on vaccine policy, research, and public health each week. This report is part of Viral Truths, a resource designed to cut through the noise, offering concise information to help navigate the evolving immunization landscape.

This week’s report is a special edition focused specifically on developments related to the CDC’s revision of its Autism and Vaccines webpage. Our regularly scheduled broader vaccine policy coverage will return next week.

THE ISSUE AT A GLANCE

  • Under HHS Secretary Kennedy’s direction, the CDC changed language on its Autism and Vaccines webpage to imply a potential link between infant vaccines and autism
  • The move directly contradicts decades of scientific evidence, including analyses involving millions of children across the globe
  • The move prompted immediate and sharply critical reactions from the medical community, public health officials, and policymakers

NEED TO KNOW

CDC Revises Language on Vaccine-Autism Link, Contradicting Decades of Established Science

  • On Thursday (November 20), the Centers for Disease Control and Prevention (CDC) updated its Autism and Vaccines webpage, replacing its longstanding statement that vaccines do not cause autism with the claim that “studies have not ruled out the possibility that infant vaccines cause autism.”
    • Researchers immediately pushed back, underscoring that decades of rigorous research have found no link between vaccines and autism. More than 40 high-quality studies—including analyses involving millions of children—have consistently shown no association.
    • Taken together, the collective evidence provides us with a high degree of confidence that vaccines are not associated with autism.
  • The revised webpage also asserts that studies suggesting a vaccine-autism link have been ignored by federal health authorities, though does not cite any evidence supporting such a claim, and notes the Department of Health and Human Services (HHS) has launched a “comprehensive assessment of the causes of autism.”
    • The few studies often promoted by vaccine skeptics have been fully retracted or widely discredited due to methodological flaws, biased samples, or failure to meet scientific standards for rigor, replication, and peer review.
  • HHS Secretary Robert F. Kennedy Jr. told reportershe personally directed CDC to make the changes, even as he acknowledged that large-scale studiesof both the measles, mumps, rubella (MMR) vaccine and of the vaccine ingredient thimerosalhave found no association with autism.
    • The updated page still includes the header “Vaccines do not cause Autism,” but with an asterisk noting the phrase has not been removed due to an agreement with Senator Bill Cassidy, who supported Kennedy’s confirmation based on assurances that the language would not change. The immediate next sentence says the heading is “not an evidence-based claim.”
    • According to multiple CDC sources, the changes were made without review or input from CDC career scientists, bypassing the agency’s standard scientific clearance process.
  • Kennedy and allied vaccine-skeptic groups say the revisions reflect a commitment to transparency and “gold standard science,” and will support deeper research into autism.
  • But CDC career staff, public health experts, autism advocacy organizations, and independent scientists warn that the edits contradict abundant evidence showing no link between vaccines and autism, and that current research continues to point toward genetic and prenatal environmental factors instead.
    • They caution that the CDC’s new language risks legitimizing false information, confusing the public, discouraging vaccination, and ultimately increasing the risk of outbreaks of dangerous preventable diseases.

Medical Community, Leaders, and Experts Respond to CDC Revision with Warnings and Condemnation

  • The webpage edits prompted immediate, sharply critical reactions from the medical, public health, and scientific communities.

Medical Societies & Public Health Groups

Medical Experts & Leaders

  • Key public health leaders and experts also voiced concerns, emphasizing that the updated language undermines scientific integrity, threatens public health, and distracts from real research.
    • Dr. Paul Offit, pediatrician and vaccine safety expert, criticized the revised language for falsely implying uncertainty, noting that numerous large studies show vaccines do not cause autism and warning that the change “promotes fear of vaccines despite overwhelming evidence to the contrary.”
    • Alison Singer, co-founder of the Autism Science Foundation, asserted that a significant body of evidence demonstrates clearly and conclusively that “vaccines do not cause autism,” underscoring in an official statementthat “no environmental factor has been better studied as a potential cause of autism than vaccines.”
    • Dr. Yvonne Maldonado, a pediatrician and infectious disease expert, condemned the move as completely ungrounded: “It is absolutely definitive. There is no link between autism and vaccines. Zero. None.”

Current & Former Government Officials

  • Senator Bill Cassidy (R-LA)—who supportedKennedy’s confirmation as HHS secretary only after receiving assurances he would not undermine vaccine safety systems—has publicly condemned the change, saying in interviews and online poststhat suggesting a vaccine-autism link is “wrong, irresponsible, and actively makes Americans sicker,” and emphasizing that “families are getting sick and people are dying from vaccine-preventable diseases.”
  • Dr. Jerome Adams, former Surgeon General, called the move “dangerous revisionism,” saying, “Under RKF’s direction the CDC just rewrote its vaccine safety page to sow doubt on the debunked myth that vaccines cause autism…science isn’t ‘both sides,’ it’s evidence…This erodes trust, spikes hesitancy and invites outbreaks.”
  • Former CDC leaders also raised concerns:
    • Dr. Mandy Cohen, former CDC Director, warned the change “undermines the agency’s scientific integrity and risks endangering children… leaving kids vulnerable to preventable diseases.”
    • Dr. Debra Houry, until recently the agency’s Chief Medical Officer, said “when you remove science from scientific information you get ideology,” adding she “would not trust information on autism from CDC.”
    • Dr. Demetre Daskalakis, former Director of the National Center for Immunization and Respiratory Diseases, said the autism page was “updated to cause chaos without scientific basis,” urging the public not to rely on CDC for autism information.

REALITY CHECK

These fact checks respond to several recent claims made by different groups and individuals.

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.

  • REALITY: The claim that studies “have not ruled out the possibility that infant vaccines cause autism” is a misrepresentation of scientific evidence—in fact, no other environmental factor has been better studied as a potential cause of autism than vaccines.
  • Decades of research—including large-scale studiesthat, combined, have analyzed millions of children—have consistently found no causal link between vaccines.
  • Notably the original theory linking vaccines to autism was based on a single, small, and now-discredited study from nearly 30 years ago that relied on flawed methods, selective data, and unethical practices. The 1998 study was fully retracted following investigations that found serious errors and misconduct.

CLAIM: Studies supporting a link between vaccines and autism have been ignored by health authorities.

  • REALITY: Health authorities have not ignored studies claiming a vaccine-autism link. In fact, the issue has been extensively reviewed—including through US government supported, taxpayer funded research—and dozens of high-quality studies have found no association. Further, vaccines remain among the most rigorously examined environmental factors in autism research.
  • As mentioned above, a now-retracted study sparked the rise of the childhood vaccine safety concerns, particularly around a potential link between vaccines and autism.
    • The Lancet retracted the study because it was “incorrect.” The authors were found guilty of scientific misrepresentations and ethical violations, and the British Medical Journal published a series of articles exposing their deliberate fraud.
  • Despite a lack of evidence connecting vaccines and autism—and substantial evidence finding no association between the two—vaccine skeptics continue to cite a handful of discredited studies, which include:
    • A 2014 paper which claimed that African American boys vaccinated before age 3 had higher autism rates, but was retracted due to undeclared competing interests and invalid methods and statistical analysis.
    • A 2015 study alleging conflicts of interest in studies of vaccines and autism that was retracted because the authors themselves failed to disclose conflicts of interest and because the study contained “a number of errors and mistakes…that raise concerns about the validity of the conclusion.”
    • A 2024 paper claiming prenatal vaccine exposure caused autism-like behaviors in rats that was retracted due to inconsistencies in the data.

CLAIM: Studies showing no link between the measles, mumps, and rubella (MMR) vaccine and autism are insufficient because they rely on observational evidence only. 

  • REALITY: Major scientific bodies have repeatedly concluded—based on high-quality evidence—that the MMR vaccine does not cause autism.
    • The CDC correctly notes that both the Institute of Medicine (now the National Academy of Medicine) and the HHS Agency for Healthcare Research and Quality (AHRQ) “maintain with a high strength of evidence that there is no association with autism spectrum disorders.”
    • The CDC’s revised wording, however, implies this conclusion may be less reliable because the data are “observational only.”
  • These studies are observational out of necessity and ethical considerations. The MMR vaccine was licensed in 1971 after being proven safe and effective—and the vaccine’s three components (the separate measles, mumps, and rubella vaccines) were approved before that. Conducting a randomized trial today would require withholding a long-proven lifesaving vaccine from some children.
    • As vaccine expert Dr. Paul Offit explained, “You can’t ethically not give vaccines to children knowing that diseases are out there that could cause them to suffer or die.”
  • Further, the MMR vaccine has been scrutinized more even extensively than other vaccines, specifically because of the now-retracted fraudulent study that sparked autism fears.
    • In the years following that study, scientists conducted numerous large, rigorous observational studies involving millions of children.
    • Every high-quality study has reached the same conclusion: there is no credible evidence of a link between the MMR vaccine and autism.
  • This body of evidence demonstrates the opposite of what skeptics suggest: when concerns arise, the scientific community investigates them thoroughly. The consistency of findings across decades, countries, and study designs is precisely what makes the evidence strong—even without randomized trials.

CLAIM: Aluminum—an ingredient used in some vaccines—may be the ingredient that is linked to autism.

  • REALITY: The claim that aluminum in vaccines may be associated with autism is not supported by scientific evidence.
  • Aluminum salts—which are used in tiny amounts in some vaccines as adjuvants to boost immune response—have been studied for decades and the safety of this ingredient and any possible impacts on neurodevelopment have been specifically researched.
  • It is worth noting that the amount of aluminum used in vaccines is extremely small—less than what infants routinely ingest through breast milk, formula, or food—and it is processed and cleared by the body in the same way.
    • Further, research also shows that aluminum adjuvants do not cross the blood-brain barrier in harmful amounts and do not accumulate to levels associated with neurological risk.
  • Numerous large-scale epidemiological studies have examined the safety of aluminum exposure from vaccines and have found no association between use of the ingredient in vaccines and autism or other neurodevelopmental disorders.

WHAT TO WATCH

Updated CDC Page Indicates Aluminum May be Discussed at ACIP December Meeting

  • The updated CDC Autism and Vaccines webpagerepeatedly signals a focus on aluminum, indicating that this may be a topic of discussion at the upcoming Advisory Committee on Immunization Practices (ACIP) meeting, which is set for December 4-5.
  • The December agenda includes a discussion of “adjuvants and contaminants.” Aluminum adjuvants(also called aluminum salts) boost immune response, allowing vaccines to work effectively with smaller or fewer doses.
    • Vaccines containing adjuvants undergo extensive testing before being approval, and there is ample evidence that aluminum adjuvants are safe.
  • Despite a lack of data, Kennedy has long claimed that aluminum in vaccines is tied to a host of issues, including autism, asthma, autoimmune disease, and food allergies—and he has recently intensified his attacks on the ingredient.
  • Any actions ACIP takes related to aluminum could have major consequences, as many critical vaccines—including those for hepatitis A, hepatitis B, diphtheria, tetanus, human papillomavirus (HPV), and pneumococcal disease—rely on aluminum adjuvants.
    • Reformulating or replacing these vaccines could take up to a decade and cost more than $1 billion each, leading to major disruptions in vaccine supply.
    • Even if they choose not to recommend reformulating or replacing any vaccines, casting doubt on their safety—as Kennedy is already doing—could cause a decrease in vaccination.

Vaccinate Your Family is a nonpartisan organization dedicated to protecting people of all ages from vaccine-preventable diseases. To learn more, visit us at: vaccinateyourfamily.org

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