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Vaccines do not cause autism

CLAIM: Vaccines cause autism.

FALSE. Many scientists have studied this question, but no credible studies show that autism is caused by vaccines.

Claims that vaccines cause autism are not true.

In 1998, a paper in the scientific journal The Lancet suggested a possible link between the measles, mumps, and rubella (MMR) vaccine and problems with brain development. The study caused people to believe that the vaccine causes autism. Later, the study was found to have serious errors. The researchers hand-picked participants to support the result they were looking for in the study. Then they did not tell the truth about how the participants were chosen. This meant the study was both unethical and not scientifically valid. In 2010 the journal retracted the paper because the results reported in it could not be trusted.

Over the past two decades, many scientists have done large, rigorous studies to find out if any aspect of vaccines could cause autism. For example, scientists compared vaccinated children who do and do not have autism, and compared children who have and have not gotten vaccines. Some studies focus on specific vaccine ingredients, such as preservatives like thimerosal or aluminum-containing adjuvants. Others focus on the possible effects of getting multiple vaccines in a short period of time.

None of these studies show any links between vaccines and autism.


Scientists are studying the real causes of autism.

Over the past few years, scientists have made many discoveries about what causes autism in a child's brain.

Autism-related patterns of brain structure and growth can be seen well before a child receives any vaccines. In fact, some studies suggest that early signs of autism begin even while a baby is still in the womb.

Scientists have found several genetic factors that seem to affect a child's chance of getting autism. It is also possible that exposure to toxic chemicals or infections during early pregnancy could lead to autism.

So far, no studies have shown that vaccines given either during pregnancy or after birth cause autism.


It is safer to get vaccines than not to.

While vaccines do not cause autism, they can sometimes have side effects.

A person’s chance of having a bad reaction to a vaccine is about one in 1 million, lower than the chance of being struck by lightning. On the other hand, not getting a recommended vaccine puts you and those around you at risk for dangerous diseases.

Unless your doctor tells you otherwise, getting a recommended vaccine is better than risking the illnesses vaccines are made to prevent.


Updated October 2019