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.

Recent estimates from CDC's Autism Developmental Disabilities Monitoring network found that about 1 in 88 children have ASD. This estimate is higher than estimates from the early 1990s. Over the years, some people have had concerns that autism might be linked to the vaccines children receive. 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 frequency does not support such an association between thimerosal and autism. Furthermore, 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 containing thimerosal and autism rates in children.

The IOM also recently conducted a thorough review of the current medical and scientific evidence on vaccines and certain health events that may be observed after vaccination. It released a report in August 2011 on 8 vaccines given to children and adults that found the vaccines to be generally safe and serious adverse events following these vaccinations to be rare.

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–

1. Understanding the frequency and trends of autism spectrum disorders.
2. Advancing research in the search for causes and effective treatments.
3. Improving early detection and diagnosis so affected children are treated as soon as possible

More Information

• 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

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.

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

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.

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.

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 (2010) Prenatal and Infant Exposure to Thimerosal from Vaccines and Immunoglobins and Risk of Autism [PDF - 365 KB]. Pediatrics 126(4): 656-664.