On November 19, under orders from HHS Secretary, RFK Jr, the CDC modified its webpage discussing Vaccines and Autism by adding asterisk to the header, “Vaccines do not cause Autism”. The message of the page was the opposite of the header, asserting that we don’t know that vaccines don’t cause autism. (An annotated version of that webpage is included at the bottom of this document.)
“The rise in autism prevalence since the 1980s correlates with the rise in the
number of vaccines given to infants”
CDC, 11/19/2025
The evidence below indicates that:
- The rise in autism is primarily if not entirely an artifact of changes in the disease definition and improved detection of autism.
- The relationship between trends in autism diagnoses and increases in childhood vaccinations is not consistent with causality.
- There is strong evidence that the MMR (Measles, Mumps, Rubella) vaccine does NOT cause.autism.
- There is no evidence that any other childhood vaccine causes autism.
Issue 1: The Autism “Epidemic”
Bottom Line: Yes, the number of people diagnosed with autism has risen dramatically, but, among those who study and care for people with autism, the reasons for that increase seem clear.
This is NOT an epidemic. It primarily, if not exclusively, represents a shift in the way we define and detect the condition.
Let’s consider the best available evidence on this.
Key Facts
- Autism did not exist as a DSM diagnostic category until 1980.
- Diagnostic criteria expanded in 1987, 1994, and 2000.
- “On the spectrum” became formalized with the creation of Autism Spectrum Disorder in 2013.
- No objective biomarker exists; diagnosis is inherently subjective.
- Failure to adjust for diagnostic drift renders trend comparisons meaningless.
The Experts Weigh In
Johns Hopkins School of Public Health
“There are two main reasons for the increase. The first is the broadened definition of Autism Spectrum Disorder, which means that more people are meeting this definition now than previously.
Second, there have been many widely successful public health programs that increased screening at wellness visits for children ages 18–24 months to look for signs of autism. Parents, caregivers, and community members are also more aware of the symptoms, and autism is being more accepted in the community. People are not as afraid to seek help and know where to go when they have concerns. “
“The data has shown that rates of autism for that subgroup have increased minimally, if at all, over the past nearly 10 years. “
Christine Ladd-Acosta, PhD, vice director of the Wendy Klag Center for Autism and Developmental Disabilities at Johns Hopkins University
Harvard School of Public Health
” …the codification of autism in the DSM-III in 1980 and the subsequent inclusion of Asperger’s syndrome in the DSM-IV in 1994 (later to be combined into a single autism spectrum disorder diagnosis in the DSM-5 in 2013) would lead to substantial increases in autism diagnosis.”
– Ari Ne’eman, Harvard School of Public Healthhttps://www.statnews.com/2025/09/30/rfk-jr-autism-diagnosis-epidemic-ussr-jfk-delegation/
Key References
“Prevalence findings from special education data do not support the claim of an autism epidemic because the administrative prevalence figures for most states are well below epidemiological estimates. The growing administrative prevalence of autism from 1994 to 2003 was associated with corresponding declines in the usage of other diagnostic categories.”
The rise in autism was matched by a decline in other, similar diagnoses.
The Autism Service “received a total of 985 referrals for autism diagnostic assessment. The Autism Service accepted 185 referrals for triage. The remaining cohort of referrals was deemed clinically inappropriate and was not triaged for assessment.”
The study involved detailed evaluations of 60 patients not accepted for triage.
“None of the evaluation cases resulted in a clinical diagnosis of ASD”
Primary car doctors tend to over diagnose autism.
“The rise in clinical diagnoses of [Autism Spectrum Disorder] in the adolescent/young adult population does not seem to be paralleled by a similar increase in ASD symptoms.”
An objective assessment of trends in the symptoms of autism found NO rise in those symptoms during a period of dramatic increases in the numbers of reported cases
Issue 2: The Trend Lines
📈 The Timeline Problem
Even if some of the rise in the diagnosis of autism did reflect an increase in disease, if vaccines were responsible, autism diagnoses would change in predictable ways following major vaccine introductions.
They don’t.
Key Facts
- Polio vaccine (1960) → no change in autism diagnoses
- MMR vaccine (1971) → no change
- Autism diagnoses rise only after 1980, following DSM shifts
- Vaccines increase in steps; autism diagnoses rise smoothly
- No vaccine schedule change corresponds with any inflection in autism prevalence
Interpretation:
The curves conflict.
This is extremely weak evidence of an association.
Issue 3: Other Evidence on Vaccines and Autism
“In fact, there are still no studies that support the claim that any of the 20 doses of the seven infant vaccines… do not cause autism.” – CDC Page
Assessment
This framing demands the impossible: proof of a universal negative.
Science does not produce “proof of no effect.”
It evaluates hypotheses using available evidence.
And this hypothesis has been studied exhaustively.
Key Facts
The Evidence Base
- More than 1,200 studies
- 10 meta-analyses
- 8 Institute of Medicine reports
- AHRQ systematic review
The Experts Weigh In
American Academy of Pediatrics
“Multiple studies from around the world have found no credible link between autism and vaccines. Continuing to push this false science poses significant risks to public health, particularly during one of the worst measles outbreaks in decades. It is also hurtful to the autistic community and a disservice to the thousands of autistic children and adults living rich, fulfilling lives.”
— Kristin Sohl, MD, FAAP
Key References
- Maglione, Margaret A, Courtney Gidengil, Lopamudra Das, et al. Safety of Vaccines Used for Routine Immunization in the United States. Agency for Healthcare Research and Quality, 2014.
“Strength of Evidence = High: No association with autism spectrum disorders.” - Adverse Effects of Vaccines: Evidence and Causality. National Academies Press, 2012. https://doi.org/10.17226/13164.
“The evidence favors rejection of a causal relationship between MMR vaccine and autism.”
The revised CDC website cites these reports — then ignores their conclusions.