Concerns about Autism
As the country's leading public health agency, the Centers for Disease Control and Prevention (CDC) is committed to protecting the health of all Americans–including infants, children, and adolescents. CDC shares with parents and many others great concern about the number of children with autism spectrum disorders (ASD). We are committed to understanding what causes autism, how it can be prevented, and how it can be recognized and treated as early as possible.
Estimates released in 2014 from CDC's Autism Developmental Disabilities Monitoring Network found that about 1 in 68 children born in 2002 have ASD. This is higher than estimates from the early 1990s. Over the years, some people have been concerned that autism might be linked to the vaccines children receive. Concerns have related to different aspects of vaccines, including vaccine ingredients.
In addition to the antigens- the parts of vaccines that protect against each specific disease- some vaccines contain other ingredients. One vaccine ingredient that has been studied specifically is thimerosal, previously used as a preservative in many recommended childhood vaccines. However, in 2001 thimerosal was removed or reduced to trace amounts in all childhood vaccines except for one type of influenza vaccine, and thimerosal-free alternatives are available for influenza vaccine. Evidence from several studies examining trends in vaccine use and changes in autism in children does not support such an association between thimerosal and autism. And a scientific review by the Institute of Medicine (IOM) concluded that "the evidence favors rejection of a causal relationship between thimerosal–containing vaccines and autism." CDC supports the IOM conclusion that there is no relationship between vaccines and autism rates in children. Besides thimerosal, some people have had concerns about other vaccine ingredients in relation to autism as well. However, no links have been found between any vaccine ingredients and autism.
In August 2011, the IOM published a report thoroughly reviewing the current medical and scientific evidence on vaccines and certain health problems that may happen after vaccination. This report found the eight studied vaccines to be generally safe, and serious adverse events following these vaccinations to be rare. Another more recent review also confirmed this.
CDC recognizes that autism is an urgent health concern and supports comprehensive research as our best hope for understanding the causes of autism and other developmental disorders. Through collaborations with partners in government, research centers, and the public, CDC is focusing on three areas:
- Understanding the frequency and trends of autism spectrum disorders.
- Advancing research in the search for causes and effective treatments.
- Improving early detection and diagnosis so affected children are treated as soon as possible.
- Vaccines not associated with risk of autism
- Autism Spectrum Disorders: What You Should Know
- IOM Report: Adverse Effects of Vaccines: Evidence and Causality, 2011
- CDC Studies on Vaccines and Autism [PDF - 30 KB]
- Timeline: Thimerosal in Vaccines (1999--2010)
- Frequently Asked Questions about Thimerosal
- Measles, Mumps, and Rubella (MMR) Vaccine
Related Scientific Articles
Hurley AM, Tadrous M, Miller ES. Thimerosal-containing vaccines and autism: a review of recent epidemiologic studies. J Pediatr Pharmacol Ther. 2010 Jul;15(3):173-81.
Price CS, Thompson WW, Goodson B, Weintraub ES, Croen LA, Hinrichsen VL, Marcy M, Robertson A, Eriksen E, Lewis E, Bernal P, Shay D, Davis RL, DeStefano F. Prenatal and infant exposure to thimerosal from vaccines and immunoglobulins and risk of autism. Pediatrics. 2010 Oct;126(4):656-64. doi: 10.1542/peds.2010-0309. Epub 2010 Sep 13.
Hornig M, Briese T, Buie T, Bauman ML, Lauwers G, et al. (2008) Lack of Association between Measles Virus Vaccine and Autism with Enteropathy: A Case-Control Study. PLoS ONE 3(9): e3140. doi:10.1371/journal.pone.0003140
McMahon AW, Iskander JK, Haber P, Braun MM, Ball R. Inactivated influenza vaccine (IIV) in children < 2 years of age: Examination of selected adverse events reported to the Vaccine Adverse Event Reporting System (VAERS) after thimerosal-free or thimerosal-containing vaccine. Vaccine 2008;26(3):427–429.
Pichichero ME, Gentile A, Giglio N, et al. Mercury levels in newborns and infants after receipt of thimerosal-containing vaccines [PDF - 404 KB]. Pediatrics 2008;121:e208-214.
Schechter R, Grether JK. Continuing increases in autism reported to California’s developmental services system: mercury in retrograde. Arch Gen Psychiatry 2008;65:19-24.
Thompson WW, Price C, Goodson B, et al. Early thimerosal exposure and neuropsychological outcomes at 7 to 10 Years. N Engl J Med 2007;357:1281-92.
William W Thompson et al publish Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 Years. N Engl J Med 2007; 357:1281-1292
Mandell DS, Thompson WW, Weintraub ES, Destefano F, Blank MB. Trends in diagnosis rates for autism and ADHD at hospital discharge in the context of other psychiatric diagnoses. Psychiatr Serv. 2005 Jan;56(1):56-62.
Burbacher TM, Shen DD, Liberato N, et al. Comparison of blood and brain mercury levels in infant monkeys exposed to methylmercury or vaccines containing thimerosal. Environ Health Perspect 2005;113:1015–21.
DeStefano F, Bhasin TK, Thompson WW, Yeargin-Allsopp M, Boyle C (2004) Age at first measles-mumps-rubella vaccination in children with autism and school-matched control subjects: a population-based study in metropolitan Atlanta. Pediatrics 113: 259–266.
Immunization Safety Review Committee. Immunization Safety Review. Vaccines and Autism Board of Health Promotion and Disease Prevention, Institute of Medicine (National Academy Press, Washington, DC, 2004).
Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism [PDF - 145 KB]. JAMA 2003;290:1763–6.
Paul Stehr-Green, et al, publish Autism and Thimerosal-Containing Vaccines, Lack of Consistent Evidence for an Association, American Journal of Preventive Medicine. American Journal of Preventive Medicine, Volume 25, Issue 2, Pages 101-106, August 2003.
Thomas Verstraeten, et al, publish Safety of Thimerosal-Containing Vaccines: A Two-Phased Study of Computerized Health Maintenance Organization Databases [PDF - 121 KB], Pediatrics 2003.
Pichichero ME, Cernichiari E, Lopreiato J, Treanor J. Mercury concentrations and metabolism in infants receiving vaccines containing thimerosal: a descriptive study. Lancet 2002;360(9347):1737–1741.
Ball L, Ball R, Pratt RD. An assessment of thimerosal in childhood vaccines. Pediatrics 2001;107:1147–1154.
Joint statement of the American Academy of Pediatrics (AAP) and the United States Public Health Service (USPHS). Pediatrics 1999;104:568–9.
Agency for Toxic Substances and Disease Registry, Public Health Service, U.S. Department of Health and Human Services. Toxicological Profile for Mercury (Update). Atlanta, GA, 1999.
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