Is there a connection between vaccines and ASD?

by CDC

Vaccines and Autism Theory

At a glance: The weight of currently available scientific evidence does not support the hypothesis that vaccines cause autism. We recognize there is considerable public interest in this issue, and therefore support additional research regarding this hypothesis. CDC is committed to maintaining the safest, most effective vaccine supply in history.

MMR Vaccine and Autism (Measles, Mumps, and Rubella)

What You Should Know

• ccine protects children against dangerous, even deadly, diseases.
• Because signs of autism may appear at around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism.
• Carefully performed scientific studies have found no relationship between MMR vaccine and autism.
• The CDC continues to recommend two doses of MMR vaccine for all children.

Additional Facts

MMR is a combination vaccine that protects children from measles, mumps, and rubella (also known as German measles). The first dose of the vaccine is usually given to children 12 to 15 months old. The second dose is usually given between 4 and 6 years of age.

In 1998, a study of autistic children raised the question of a connection between MMR vaccine and autism.

The 1998 study has a number of limitations. For example, the study was very small, involving only 12 children. This is too few cases to make any generalizations about the causes of autism. In addition, the researchers suggested that MMR vaccination caused bowel problems in the children, which then led to autism. However, in some of the children studied, symptoms of autism appeared before symptoms of bowel disease.

In 2004, 10 of the 13 authors of the 1998 study retracted the study's interpretation. The authors stated that the data were not able to establish a causal link between MMR vaccine and autism.

Other larger studies have found no relationship between MMR vaccine and autism. For example, researchers in the UK studied the records of 498 children with autism born between 1979 and 1998. They found: the percentage of children with autism who received MMR vaccine was the same as the percentage of unaffected children in the region who received MMR vaccine, there was no difference in the age of diagnosis of autism in vaccinated and unvaccinated children, the onset of "regressive" symptoms of autism did not occur within 2, 4, or 6 months of receiving the MMR vaccine.

Groups of experts, including the American Academy of Pediatrics, agree that MMR vaccine is not responsible for recent increases in the number of children with autism. In 2004, a report by the Institute of Medicine (IOM) concluded that there is no association between autism and MMR vaccine or vaccines that contain thimerosal as a preservative.

There is no published scientific evidence showing that there is any benefit to separating the combination MMR vaccine into three individual shots.

MMR Vaccine & Autism FAQ

What is autism?

Autism is a term that refers to a collection of neurologically-based developmental disorders in which individuals have impairments in social interaction and communication skills, along with a tendency to have repetitive behaviors or interests. The severity of autism varies greatly, from individuals with little speech and poor daily living skills, to others who function well in most settings. Autism is typically diagnosed during the toddler or preschool years, although some children are diagnosed at older ages. It has been reported that approximately 20 percent of children with autism experience a "regression;" that is, they have apparently normal development followed by a loss of communication and social skills. Boys are three-to-four times more likely to have autism than girls. Autism occurs in all racial, ethnic, and social groups. A variety of factors could be associated with some forms of autism, including infectious, metabolic, genetic, neurological, and environmental factors. Genetic factors and brain abnormalities at birth are considered to be some of the most recognized causes of autism.

Does the measles-mumps-rubella (MMR) vaccine cause autism?

Current scientific evidence does not support the hypothesis that measles-mumps-rubella (MMR) vaccine, or any combination of vaccines, causes the development of autism, including regressive forms of autism. The question about a possible link between MMR vaccine and autism has been extensively reviewed by independent groups of experts in the U.S. including the National Academy of Sciences, Institute of Medicine. These reviews have concluded that the available epidemiologic evidence does not support a causal link between MMR vaccine and autism.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.