Vaccines and Autism: What the Evidence Shows for Worried Parents

If you are worried about vaccines and autism, you are not alone, and your question is a fair one. The short answer is that vaccines do not cause autism. Large studies of millions of children, in many countries and over more than 20 years, have looked hard for a link and have not found one. This guide covers the evidence, recent US changes, and how to make shots easier.

Where the vaccines and autism worry began

In 1998, a doctor named Andrew Wakefield and his co-authors published a small paper in The Lancet about 12 children. It suggested a possible link between the MMR vaccine, bowel problems and autism.

Later investigations told a very different story. A journalist who reviewed the children’s medical records found that not one of the 12 cases was free of misrepresentation, and the BMJ concluded the paper was fraudulent [1]. Wakefield also had a conflict of interest because of his involvement with a lawsuit [1].

The UK General Medical Council (GMC) held its longest ever fitness to practise hearing. It found Wakefield guilty of dishonesty about how children were chosen for the study and about its funding by the Legal Aid Board [1]. He lost his medical and academic credentials [1]. In 2010, The Lancet fully retracted the paper [2], noting GMC findings that the children were not consecutively referred and the study did not have ethical approval [1].

Do vaccines cause autism? What the big studies found

MMR autism studies

• Denmark, 2002. This study followed all 537,303 children born in Denmark from 1991 to 1998. Of these, 82.0 percent got the MMR vaccine. Vaccinated children were not more likely to be diagnosed with autism than unvaccinated children. There was also no link with the age at vaccination or the time since vaccination [3].
• Denmark, 2019. A newer study followed 657,461 children born from 1999 to 2010. It found no increased risk of autism after MMR. This held true for children with an autistic brother or sister, for children with other autism risk factors, and in the time periods right after the shot [4].
• United States, 2015. This study looked at 95,727 children with older siblings, including 1,929 with an older autistic sibling. MMR was not linked to a higher chance of autism at any age, even in children whose older sibling was autistic [5].

Reviews that combine many studies

A 2014 meta-analysis pooled five cohort studies with 1,256,407 children and five case-control studies with 9,920 children. It found no link between vaccination and autism, and no link with MMR, thimerosal or mercury [6].

Thimerosal autism studies

Thimerosal is a preservative that contains a type of mercury called ethylmercury. A Danish study of 467,450 children compared kids who got a thimerosal-containing vaccine with kids who got a thimerosal-free version of the same vaccine. Autism risk was not different, and higher doses did not raise risk [7].

Aluminum adjuvants autism study (2025)

Some vaccines contain tiny amounts of aluminum. This helps the body build a stronger immune response. In July 2025, a Danish team published a study of 1,224,176 children born from 1997 to 2018. They measured how much aluminum each child got from vaccines in the first 2 years of life. More aluminum was not linked to higher rates of any of 50 chronic conditions, including autism and ADHD [8]. The authors were honest that very small effects on some rarer conditions could not be fully ruled out [8].

Why the timing can feel linked

Many parents first notice differences in their child in the months after the first birthday. That is a real and important experience. One small study followed 25 babies later diagnosed with autism, and 25 who were not, from 6 months of age. At 6 months, the two groups looked very similar. Over time, though, they showed less eye contact, fewer shared smiles and fewer sounds directed at others. The differences were clear by 12 months for most measures [9].

In the US, the first MMR dose is given at 12 to 15 months [10]. In the UK, children are now offered the combined MMRV vaccine at 12 and 18 months [11]. So the shot and the first noticeable signs often happen at about the same time, even though one does not cause the other. The large Danish study also found no clustering of autism cases in the months after MMR [4]. See our guides on what causes autism and early signs in toddlers.

What major health bodies say about vaccines and autism

• World Health Organization. WHO’s vaccine safety committee concluded that “no evidence exists of a causal association between MMR vaccine and autism or autistic disorders” [12].
• NHS (UK). The NHS says, “Research has shown there is no link between the MMR vaccine and autism” [11].
• American Academy of Pediatrics (AAP). The AAP points to more than 40 high-quality studies since 1998, with over 5.6 million people in seven countries, and states, “There’s no link between vaccines and autism” [13].

A large US study found that autistic children were less likely to be fully vaccinated for the shots due at ages 4 to 6. Their younger siblings were also under-vaccinated. The authors said this leaves these children at higher risk of diseases that vaccines prevent [14].

What changed in the US in 2025 and 2026

• June 2025. Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. removed all 17 members of the CDC’s vaccine advisory committee, known as ACIP. He said, “A clean sweep is needed to re-establish public confidence in vaccine science” [15].
• November 2025. On November 19, the CDC’s “Autism and Vaccines” webpage was rewritten. It now says the statement “Vaccines do not cause autism” is not an evidence-based claim [16]. The heading still says vaccines do not cause autism, but with an asterisk and a note that it was kept because of an agreement with the chair of a Senate committee [16]. The updated page cited no new research [16]. An HHS spokesman said the site was being updated to “reflect gold standard, evidence-based science” [16]. When we checked in October 2026, the page still carried this wording [17].
• How experts responded. A FactCheck.org review found the new page leaned on a weak 2014 study by a researcher with ties to anti-vaccine groups, and cherry-picked results from the 2025 Danish aluminum study [18]. The AAP called the claims false and asked the CDC to stop spreading them [13].
• January 2026. The CDC cut the number of diseases covered by routine childhood vaccine recommendations from 17 to 11. Measles, polio and whooping cough shots stayed recommended for all children [19].
• March 2026. In a lawsuit brought by the AAP and other medical groups, a federal judge in Boston issued a preliminary injunction. It blocked the January schedule changes, the new ACIP appointments and the new committee’s decisions, finding they likely broke federal law [20].
• Now. The government appealed in April 2026, and an appeals court hearing was set for October 6, 2026 [21]. The groups that sued say the order also blocks a December 2025 vote on the hepatitis B birth dose and restores the earlier recommendations [21]. When we last checked in October 2026, no appeals ruling had been reported, so rules may still change.

The policy debate is real, but the science has not changed. No new study has shown that vaccines cause autism.

Should I vaccinate my autistic child?

Based on the research above, the major medical bodies agree that vaccines are safe for autistic children and their siblings. The Danish and US sibling studies are reassuring here, because they included the very families who often worry most [4][5].

Tips to make shots easier for sensory-sensitive kids

• Use numbing cream. A pain guideline strongly recommends a numbing cream or patch for children 12 and under [22]. Ask your doctor which one to use and when to apply it.
• Sit upright. Children aged 3 and up do better sitting up than lying down [22]. Your child can sit on your lap in a hug.
• Stay with your child. The guideline recommends parents stay in the room for children 10 and under [22].
• Ask for the most painful shot last. When more than one shot is given, giving the most painful one last can help [22].
• Prepare with pictures. A visual schedule (car, waiting room, shot, sticker, home) or a short social story shows your child what comes next.
• Plan for the senses. Bring headphones, sunglasses, a favorite toy or a chewy. Our page on sensory processing has more ideas.
• Ask for adjustments. Request a quiet room, or wait in the car until the nurse is ready.
• Use honest, calm words. Say something like “a quick pinch, then we are done,” instead of “it won’t hurt.”

Talking with your doctor about your concerns

Good doctors welcome questions. You might ask:

• “What does the research say about vaccines and autism for a child like mine?”
• “My older child is autistic. Does that change anything for my younger child’s vaccines?”
• “Which vaccines are recommended right now, given the recent changes?”
• “Can we use numbing cream, a quiet room or extra time at the visit?”

When to talk to a professional

Call your doctor if you have questions about your child’s vaccine schedule, or if your child had a strong reaction to a past vaccine. Also reach out if you notice your child losing words or skills they used to have, at any age. If your child has trouble breathing, swelling of the face or throat, or a seizure after any vaccine, call 911 in the US or 999 in the UK right away.

Frequently asked questions

Do vaccines cause autism?

No. Large studies of millions of children in many countries have found no link between vaccines and autism. This includes studies of the MMR vaccine, the preservative thimerosal and aluminum adjuvants. Major health bodies such as the WHO, the NHS and the American Academy of Pediatrics all agree. The studies even looked at the age of vaccination and the time since the shot, and still found no link.

Why did the CDC website change its wording on vaccines and autism?

In November 2025, the CDC’s webpage on autism and vaccines was rewritten. News reports said it was unclear who at the CDC or its parent agency made the change, and the page did not cite any new research. Medical groups, including the American Academy of Pediatrics, said the new wording was not supported by the evidence. The scientific findings themselves have not changed, and no new study has shown that vaccines cause autism.

My older child is autistic. Is it safe to vaccinate my baby?

Yes. Researchers have studied this exact question. Large studies in Denmark and the US included younger siblings of autistic children, and they found that the MMR vaccine did not raise their chance of autism. Autism does run in families, but vaccines do not add to that chance. Talk with your doctor about your feelings, too, since your worry is real and valid.

Is spacing out vaccines safer for autistic children?

There is no evidence that spacing out vaccines prevents autism or makes them safer. Delaying shots does leave your child unprotected for longer against serious diseases like measles and whooping cough. If many shots in one visit feel too hard for your child, talk with your doctor. Together you can make a plan that keeps your child protected and makes each visit as calm as possible.

References

1. Godlee F, Smith J, Marcovitch H. Wakefield’s article linking MMR vaccine and autism was fraudulent. BMJ. 2011;342:c7452. doi:10.1136/bmj.c7452. Link
2. The Editors of The Lancet. Retraction: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet. 2010;375(9713):445. doi:10.1016/S0140-6736(10)60175-4. Link
3. Madsen KM, Hviid A, Vestergaard M, et al. A population-based study of measles, mumps, and rubella vaccination and autism. N Engl J Med. 2002;347(19):1477-1482. doi:10.1056/NEJMoa021134. Link
4. Hviid A, Hansen JV, Frisch M, Melbye M. Measles, mumps, rubella vaccination and autism: a nationwide cohort study. Ann Intern Med. 2019;170(8):513-520. doi:10.7326/M18-2101. Link
5. Jain A, Marshall J, Buikema A, et al. Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. JAMA. 2015;313(15):1534-1540. doi:10.1001/jama.2015.3077. Link
6. Taylor LE, Swerdfeger AL, Eslick GD. Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies. Vaccine. 2014;32(29):3623-3629. doi:10.1016/j.vaccine.2014.04.085. Link
7. Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism. JAMA. 2003;290(13):1763-1766. doi:10.1001/jama.290.13.1763. Link
8. Andersson NW, Bech Svalgaard I, Hoffmann SS, Hviid A. Aluminum-adsorbed vaccines and chronic diseases in childhood: a nationwide cohort study. Ann Intern Med. 2025;178(10):1369-1377. doi:10.7326/ANNALS-25-00997. Link
9. Ozonoff S, Iosif AM, Baguio F, et al. A prospective study of the emergence of early behavioral signs of autism. J Am Acad Child Adolesc Psychiatry. 2010;49(3):256-266. doi:10.1016/j.jaac.2009.11.009. Link
10. Centers for Disease Control and Prevention. Measles vaccination. Updated April 29, 2026. Link
11. NHS. MMR (measles, mumps and rubella) vaccine. Page last reviewed March 8, 2024. Link
12. World Health Organization, Global Advisory Committee on Vaccine Safety. MMR and autism. GACVS meeting of December 16-17, 2002. Link
13. American Academy of Pediatrics. Statement by AAP President Susan J. Kressly, MD, FAAP, on changes to CDC’s website on autism. November 20, 2025. Link
14. Zerbo O, Modaressi S, Goddard K, et al. Vaccination patterns in children after autism spectrum disorder diagnosis and in their younger siblings. JAMA Pediatr. 2018;172(5):469-475. doi:10.1001/jamapediatrics.2018.0082. Link
15. HLTH. RFK Jr. removes entire CDC vaccine advisory committee. June 10, 2025. Link
16. Stobbe M (Associated Press). CDC “vaccine safety” webpage changed to contradict scientific conclusion that vaccines don’t cause autism. PBS NewsHour. November 20, 2025. Link
17. Centers for Disease Control and Prevention. Autism and vaccines. Last updated July 22, 2026 (accessed October 2026). Link
18. McDonald J, Yandell K. Revised CDC website about autism and vaccines is not evidence-based. FactCheck.org. November 20, 2025. Link
19. American Journal of Managed Care. CDC reduces US childhood immunization schedule from 17 to 11 diseases. January 5, 2026. Link
20. Dall C. Federal judge blocks Kennedy’s changes to childhood vaccine policy. CIDRAP, University of Minnesota. March 2026. Link
21. Vega E. Judge pauses pediatricians’ lawsuit over Kennedy’s vaccine changes as families await October 6 appeals court argument. Medical Daily. September 15, 2026. Link
22. Taddio A, McMurtry CM, Shah V, et al. Reducing pain during vaccine injections: clinical practice guideline. CMAJ. 2015;187(13):975-982. doi:10.1503/cmaj.150391. Link

Professional review: this guide is waiting for review by a qualified clinician. It was written and checked against the published sources listed above. How we check our guides.

This guide is general education, not medical advice. Always talk to your child’s doctor or care team. Last checked: October 2026.