Executive Summary
"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 WHO's Global Advisory Committee on Vaccine Safety reviewed 31 studies from 11 countries (Jan 2010–Aug 2025) and reaffirmed: "There is no evidence of a causal relationship between vaccines and autism." Over 5.6 million people have been studied with the same conclusion.
The Real-World Impact: 2025 Measles Crisis
The CDC website changes come amid the worst measles outbreak in the United States since 2000—the year measles was declared eliminated. The correlation between vaccine hesitancy messaging and outbreak severity is stark.
U.S. Risks Losing Measles Elimination Status
CDC data shows kindergarten MMR vaccination coverage has dropped from 95.2% (2019-2020) to 92.7% (2023-2024)—below the 95% threshold needed for herd immunity. The U.S. risks losing its measles elimination status if trends continue.
Timeline: The Erosion of Vaccine Guidance
The Scientific Evidence
What the WHO Review Found
The WHO's systematic review analyzed 31 primary research studies and 5 meta-analyses spanning January 2010 to August 2025. The findings:
- 20 of 31 studies (including the most methodologically rigorous) found no association
- All 5 meta-analyses found no association
- Studies covered 11 different countries
- Reaffirmed conclusions from 2002, 2004, and 2012 reviews
On Aluminum Adjuvants
The CDC's new page specifically questions aluminum adjuvants. WHO addressed this directly: two ecological studies reporting associations were "judged at critical risk of bias" with "very low" evidence quality. A large Danish cohort study using "robust methodology" found no association between aluminum-adsorbed vaccines and autism or other neurodevelopmental disorders.
"More than 40 high-quality studies involving over 5.6 million people across seven countries. The conclusion is clear and unambiguous: There's no link between vaccines and autism."
— Dr. Susan J. Kressly, President, American Academy of Pediatrics
Medical Community Response
The response from medical organizations has been swift and unanimous in condemning the CDC's new messaging:
"Despite recent changes to the CDC website, an abundance of evidence from decades of scientific studies shows no link between vaccines and autism. Extensive and rigorous studies consistently show that vaccines are safe and effective."
— American Medical Association, Official Statement
"The scientists did not participate in its creation. The data are unvetted."
— Dr. Demetre Daskalakis, Former CDC Official
State-Level Pushback
Massachusetts health officials are removing links to federal health data from state web pages. Commissioner Dr. Robbie Goldstein called the CDC's new assertions "dangerous and alarming" and said they will "confuse the public, increase vaccine hesitancy, and result in the spread of preventable diseases."
WHO's Direct Refutation
On December 11, 2025—weeks after the CDC website change—the World Health Organization's Global Advisory Committee on Vaccine Safety issued a direct response:
WHO GACVS Conclusion (December 11, 2025)
"The available high-quality scientific evidence indicates that vaccines, including those with thiomersal or aluminium or both, do not cause autism."
The committee emphasized that "global childhood immunisation efforts represent one of the greatest achievements in improving lives" and have saved at least 154 million lives over the past 50 years.
Bottom Line
The CDC's new vaccine-autism webpage contradicts the scientific consensus established by decades of research across 11 countries involving over 5.6 million participants. The WHO directly refuted these claims on December 11, 2025, reaffirming that vaccines do not cause autism. Meanwhile, the real-world consequences of vaccine hesitancy are already visible: the U.S. is experiencing its worst measles outbreak since 2000, with 1,958 cases, 3 deaths, and 92% of patients unvaccinated. The timing of the CDC's messaging shift—amid this public health crisis—makes it particularly concerning.