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Do Vaccines Cause Autism?

Conclusion | Why This is an Issue? | Vaccines of Interest | Epidemiological Evidence | Proposed Biological Mechanism | Archives | References


Childhood vaccines do not cause autism. Maternal vaccines have not been shown to cause autism.

The Institute of Medicine (IOM), now called the National Academy of Medicine (NAM), concluded that the body of evidence favors rejection of a causal relationship between autism and MMR vaccine and thimerosal-containing vaccines [1, 2]. MMR vaccine also prevents rubella disease, thus preventing congenital rubella syndrome and its associated cases of autism.

Why This is an Issue

Andrew Wakefield, a gastroenterologist at the Royal Free Hospital in England, published a case series in the medical journal The Lancet in 1998. In this article he described 12 children with pervasive developmental disorder associated with gastrointestinal symptoms, 8 of whom had behavioral issues temporally associated with MMR vaccination via retrospective accounts by their parents or physicians [3]. Despite study authors acknowledging that this did not prove an association between the vaccine and autism, the lead author went far beyond the paper’s conclusions in a press release and ongoing interactions with the media [4, 5]. Public concern on the topic grew quickly. In 2010, Dr. Wakefield’s license to practice medicine in the UK was revoked by the British General Medical Council and his study was retracted by The Lancet as evidence of serious professional misconduct mounted. Among other infractions, Wakefield was found to have ordered unnecessary invasive procedures on children without approval of the hospital ethics committee and received undeclared financial considerations from the Legal Aid Board, a group pursuing multiparty legal action for allegedly vaccine-damaged children [6-11]. In addition, he had applied for patents for vaccines to rival MMR vaccine. It was also revealed that, for most of the children in the original study, their symptoms either started well before or long after MMR vaccination. Despite the complete refutation of Wakefield’s fraudulent findings by the scientific community, concern still exists among some parents.

Vaccines of Interest

While the initial vaccine targeted by Dr. Wakefield was MMR, the target has shifted over time, especially as epidemiological evidence accumulated that the MMR vaccine was not associated with autism spectrum disorder (ASD). Other targets have included the preservative thimerosal as well as simultaneous vaccination with multiple vaccines. See the Can Vaccine Ingredients Cause Adverse Events? and the Can Simultaneous Vaccination Cause Adverse Events? summaries for more details.

Epidemiological Evidence

There have been 16 methodologically sound, controlled epidemiological studies exploring an association between ASD and receipt of MMR vaccine [12-18], thimerosal in vaccines [19-23], and simultaneous vaccination with multiple vaccines [23, 24], in addition to the relevant systematic reviews [2, 26-29] and one meta-analysis [30]. Together, these studies included more than 1.8 million children. Notwithstanding 11 studies from another pair of authors [31-41], all of which had substantial methodological flaws [2, 27, 28, 42], the epidemiological evidence consistently shows no association between MMR vaccine, thimerosal in vaccines, or simultaneous vaccination and ASD.

One study suggested a possible increased risk of ASD among children whose mothers received an influenza vaccination during their first trimester of pregnancy, although this association was not statistically significant after a post hoc analysis adjusting for multiple comparisons, and there was no association between ASD and influenza vaccination received during any trimester [43]. Another study showed that receiving Tdap vaccine during pregnancy is not associated with increased risk of ASD in the child [44].

Proposed Biological Mechanism

The overlapping times of childhood vaccine administration and usual onset of ASD symptoms have led to speculations about a possible causal pathway; however, the proposed links have been unsubstantiated [45]. Several different theories were proposed to attribute the cause of ASD to vaccines. Wakefield suggested that a dysregulated immune response to measles antigen in the MMR vaccine led to persistent intestinal infection, allowing “toxins” to enter the blood stream and enter the central nervous system leading to developmental regression in children. He claimed support for this because of his alleged detection of measles virus RNA in bowel specimens of several children with ASD [3]. However, his referenced study was found to be fraudulent, and no evidence of persistent infection has been shown in studies that used appropriate methods [46-48]. Another proposed trigger for ASD was thimerosal, an ethyl-mercury containing preservative that used to be present in some vaccines, although not in the MMR vaccine. This theory was based on observed similarities in some features of ASD and mercury poisoning [49]; however, the degree of these similarities and the plausibility of this suspected association was refuted by neurologists [50]. The IOM found no valid mechanistic evidence connecting MMR or thimerosal-containing vaccines and ASD [1, 2].


1. Institute of Medicine. In: Stratton K, Ford A, Rusch E, Clayton EW, eds. Adverse Effects of Vaccines: Evidence and Causality. Washington (DC): National Academies Press (US); 2012. abstract
2. Institute of Medicine Immunization Safety Review C. The National Academies Collection: Reports funded by National Institutes of Health. Immunization Safety Review: Vaccines and Autism. Washington (DC): National Academies Press (US); 2004. abstract
3. Wakefield AJ, Murch SH, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 1998;351:637-41. abstract
4. Horton R. A statement by the editors of The Lancet. Lancet 2004;363:820-1. abstract
5. Murch SH, Anthony A, Casson DH, et al. Retraction of an interpretation. Lancet 2004;363:750. abstract
6. Eggertson L. Lancet retracts 12-year-old article linking autism to MMR vaccines. CMAJ 2010;182:E199-200. abstract
7. Retraction--Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 2010;375:445. abstract
8. Deer B. Wakefield's "autistic enterocolitis" under the microscope. BMJ 2010;340:c1127. abstract
9. Deer B. How the case against the MMR vaccine was fixed. BMJ 2011;342:c5347. abstract
10. Deer B. Secrets of the MMR scare. How the vaccine crisis was meant to make money. BMJ 2011;342:c5258. abstract
11. Deer B. Secrets of the MMR scare. The Lancet's two days to bury bad news. Bmj 2011;342:c7001. abstract
12. Taylor B, Miller E, Farrington CP, et al. Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet 1999;353:2026-9. abstract
13. Taylor B, Miller E, Lingam R, Andrews N, Simmons A, Stowe J. Measles, mumps, and rubella vaccination and bowel problems or developmental regression in children with autism: population study. Bmj 2002;324:393-6 . abstract
14. Farrington CP, Miller E, Taylor B. MMR and autism: further evidence against a causal association. Vaccine 2001;19:3632-5. abstract
15. Madsen KM, Hviid A, Vestergaard M, et al. A population-based study of measles, mumps, and rubella vaccination and autism. NEJM 2002;347:1477-82. abstract
16. Smeeth L, Cook C, Fombonne E, et al. MMR vaccination and pervasive developmental disorders: a case-control study. Lancet 2004;364:963-9. abstract
17. Mäkelä A, Nuorti JP, Peltola H. Neurologic disorders after measles-mumps-rubella vaccination. Pediatrics 2002;110:957-63.abstract
18. Hviid A, Hansen JV, Frisch M, Melbye M. Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study. Ann Intern Med 2019 Mar 5. PMID: 30831578. abstract
19. Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism. JAMA 2003;290:1763-6. abstract
20. Verstraeten T, Davis RL, DeStefano F, et al. Safety of thimerosal-containing vaccines: a two-phased study of computerized health maintenance organization databases. Pediatrics 2003;112:1039-48. abstract
21. Andrews N, Miller E, Grant A, Stowe J, Osborne V, Taylor B. Thimerosal exposure in infants and developmental disorders: a retrospective cohort study in the United kingdom does not support a causal association. Pediatrics 2004;114:584-91. abstract
22. Croen LA, Matevia M, Yoshida CK, Grether JK. Maternal Rh D status, anti-D immune globulin exposure during pregnancy, and risk of autism spectrum disorders. Am J Obstet Gynecol 2008;199:234.e1-6. abstract
23. Price CS, Thompson WW, Goodson B, et al. Prenatal and infant exposure to thimerosal from vaccines and immunoglobulins and risk of autism. Pediatrics 2010;126:656-64. abstract
24. Uno Y, Uchiyama T, Kurosawa M, Aleksic B, Ozaki N. The combined measles, mumps, and rubella vaccines and the total number of vaccines are not associated with development of autism spectrum disorder: the first case-control study in Asia. Vaccine 2012;30:4292-8. abstract
25. DeStefano F, Price CS, Weintraub ES. Increasing exposure to antibody-stimulating proteins and polysaccharides in vaccines is not associated with risk of autism. The Journal of pediatrics 2013;163:561-7. abstract
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28. Schultz ST. Does thimerosal or other mercury exposure increase the risk for autism? A review of current literature. Acta neurobiologiae experimentalis 2010;70:187-95. abstract
29. Maglione MA, Das L, Raaen L, et al. Safety of vaccines used for routine immunization of U.S. children: a systematic review. Pediatrics 2014;134:325-37. abstract
30. 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;32:3623-9. abstract
31. Geier MR, Geier DA. Neurodevelopmental disorders after thimerosal-containing vaccines: a brief communication. Experimental biology and medicine (Maywood, NJ) 2003;228:660-4. abstract
32. Geier DA, Geier MR. An assessment of the impact of thimerosal on childhood neurodevelopmental disorders. Pediatric rehabilitation 2003;6:97-102. abstract
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34. Geier DA, Geier MR. An evaluation of serious neurological disorders following immunization: a comparison of whole-cell pertussis and acellular pertussis vaccines. Brain & development 2004;26:296-300. abstract
35. Geier DA, Geier MR. A comparative evaluation of the effects of MMR immunization and mercury doses from thimerosal-containing childhood vaccines on the population prevalence of autism. Medical science monitor : international medical journal of experimental and clinical research 2004;10:Pi33-9. abstract
36. Geier DA, Geier MR. A two-phased population epidemiological study of the safety of thimerosal-containing vaccines: a follow-up analysis. Medical science monitor : international medical journal of experimental and clinical research 2005;11:Cr160-70. abstract
37. Geier DA, Geier MR. An evaluation of the effects of thimerosal on neurodevelopmental disorders reported following DTP and Hib vaccines in comparison to DTPH vaccine in the United States. Journal of toxicology and environmental health Part A 2006;69:1481-95. abstract
38. Geier DA, Geier MR. A meta-analysis epidemiological assessment of neurodevelopmental disorders following vaccines administered from 1994 through 2000 in the United States. Neuro endocrinology letters 2006;27:401-13. abstract
39. Geier DA, Geier MR. An assessment of downward trends in neurodevelopmental disorders in the United States following removal of Thimerosal from childhood vaccines. Medical science monitor : international medical journal of experimental and clinical research 2006;12:Cr231-9. abstract
40. Young HA, Geier DA, Geier MR. Thimerosal exposure in infants and neurodevelopmental disorders: an assessment of computerized medical records in the Vaccine Safety Datalink. J Neurol Sci 2008;271:110-8. abstract
41. Kern JK, Haley BE, Geier DA, Sykes LK, King PG, Geier MR. Thimerosal exposure and the role of sulfation chemistry and thiol availability in autism. International journal of environmental research and public health 2013;10:3771-800. abstract
42. Deer B. Autism research: What makes an expert? BMJ 2007;334:666-7. abstract
43. Zerbo O, Qian Y, Yoshida C, et al. Association Between Influenza Infection and Vaccination During Pregnancy and Risk of Autism Spectrum Disorder. JAMA Pediatr 2017:171(1):e163609. abstract
44. Becerra-Culqui TA, Getahun D, Chiu V, et al. Prenatal Tetanus, Diphtheria, Acellular Pertussis Vaccination and Autism Spectrum Disorder. Pediatrics 2018. abstract
45. Halsey NA, Hyman SL. Measles-mumps-rubella vaccine and autistic spectrum disorder: report from the New Challenges in Childhood Immunizations Conference convened in Oak Brook, Illinois, June 12-13, 2000. Pediatrics 2001;107:E84. abstract
46. Hornig M, Briese T, Buie T, et al. Lack of association between measles virus vaccine and autism with enteropathy: a case-control study. PloS one 2008;3:e3140. abstract
47. Libbey JE, Coon HH, Kirkman NJ, et al. Are there altered antibody responses to measles, mumps, or rubella viruses in autism? Journal of neurovirology 2007;13:252-9. abstract
48. D'Souza Y, Fombonne E, Ward BJ. No evidence of persisting measles virus in peripheral blood mononuclear cells from children with autism spectrum disorder. Pediatrics 2006;118:1664-75. abstract
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50. Nelson KB, Bauman ML. Thimerosal and autism? Pediatrics 2003;111:674-9. abstract

The information on this page was last updated on November 11 2020 | © 2020 Institute for Vaccine Safety