Exploring the theories and debunking the myths behind the supposed connection between vaccines and autism.

The recent rise in autism rates has left scientists and medical professionals scrambling to identify possible causes. One theory suggests that autism is caused by the use of vaccinations in young children. While this theory has gained a modest following, it is not based on scientific evidence or fact. Vaccines do not cause autism.

Why do people think vaccines cause autism? While there were previous studies that showed some correlation between vaccines and autism, these studies proved to be inaccurate. Unfortunately, it is difficult to retract incorrect information once it circulates. The medical community has worked hard to re-educate people about the benefits of vaccines and dissuade inaccuracies, but the false belief that vaccines are linked to autism is still pervasive today, often with harmful consequences.

The MMR Vaccine Controversy

One of the more prevalent theories is that the measles, mumps and rubella (MMR) vaccine causes autism. The MMR vaccine is a live-virus administered to children between the ages of 12–15 months. The controversy involving the MMR vaccine began in the 1990s when Dr. Andrew Wakefield postulated that certain children have an increased likelihood of developing autism due to compromised immune systems. The introduction of a severe health problem or a live-virus injection, such as the MMR vaccine, was believed to increase their chances of developing autism.

Dr. Wakefield’s autism theory was discredited after multiple studies were conducted that could not replicate his alleged findings. However, the long-term implications of this faulty theory are staggering, and thousands of children have not received potentially life-saving vaccines because of it.

The Thimerosal Hypothesis

During the late 1990s, thimerosal came under speculation as a potential cause of autism. Talk of the relationship between thimerosal and autism began after people realized that a thimerosal additive present in many children’s vaccines contained mercury, which is a known health hazard.

Thimerosal was removed from most children’s vaccines in 2001 to limit health risks. Upon further study of vaccinated children versus children who did not receive thimerosal-infused vaccinations, researchers found no difference in the number of children with autism diagnoses. The rate of autism continues to rise in spite of the absence of thimerosal in children’s vaccines.

Additional Theories and Repercussions

Some theorize that it isn’t a specific vaccine that causes autism, but rather the sheer number of vaccinations given to children. There has been an increase in the number of vaccines given to children in recent years, leading some to believe that this increased exposure is related to the rise in autism. Others theorize that aluminum present in some vaccines is the culprit, though this has not been supported by scientific evidence. There are higher amounts of aluminum in a variety of other sources, including breast milk and infant formula.

The Centers for Disease Control and Prevention (CDC) has stated definitively that vaccines and their ingredients do not cause autism. To prove this, the CDC released a comprehensive report that cites nine credible studies examining the relationship between vaccine and autism rates dating back to 2003.

There are serious repercussions related to false claims about autism and vaccinations. A non-vaccinated child is at risk for a host of potentially deadly illnesses. In addition to individual risk, other children who are exposed to a non-immunized child are also in danger of exposure to serious illness. Elderly people or those with compromised immune systems are also at higher risk of major health concerns when exposed to these viruses.

Parental fear of autism is legitimate, particularly in light of the increase in autism rates over the past several decades. Fear-driven decisions are not useful, however, especially when they can lead to even greater health risks. Well-intentioned parents who are trying to protect their children from one assumed risk can end up exposing them to many others.

Vaccines do not cause autism. The vaccine and autism myth has been disproven time and again by multiple studies. It’s crucial to resist the urge to give in to fear-based thinking and listen to scientific evidence. As researchers and medical professionals learn more about autism spectrum disorder, they will be better about to examine other factors more relevant to autism’s development than vaccines.

Megan Hull
Editor – Megan Hull
Megan Hull is a content specialist who edits, writes and ideates content to help people find recovery. Read more
Paula Holmes
Medically Reviewed By – Paula Holmes, LCSW
Paula Holmes is a licensed clinical social worker, psychotherapist and freelance writer who lives and works in midcoast Maine. She received her master's degree in Social Work in 2008 from the University of Maine. Read more

Rudy, Lisa Jo. “Why Do People Think the MMR Vaccine Causes Autism?” Verywellhealth.com. February 8, 2019. Accessed March 20, 2019.

Historyofvaccines.org “Do Vaccines Cause Autism?” (nd). Accessed March 22, 2019.

Cdc.gov. “Vaccines Do Not Cause Autism.” (nd). Accessed March 22, 2019.

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