Autism and Vaccines
Vaccines work with the immune system to prevent infectious diseases such as polio, measles, diphtheria, and whooping cough. Hence, vaccines are one of the greatest success stories in all of medicine. Unfortunately, immunization rates have dropped in recent years in part because of concerns about whether some vaccines may be associated with the development of autism spectrum disorder (ASD). Multiple studies conducted in several different countries have demonstrated that there is no causal association between vaccines or their preservatives and ASD. Further, vaccines do not change the timing of the onset of ASD symptoms, nor do they affect the severity of ASD symptoms. Even in families who have a greater risk for ASD, such as those who already have a child with ASD, there is no increased likelihood that the second child will have ASD if vaccinated.
Twin and family studies over the last few decades have consistently demonstrated that ASD has a strong genetic basis. Recent studies have demonstrated that brain changes associated with ASD risk most likely occur before birth and well before any immunizations are ever administered. Some environmental risk factors, such as maternal valproate use during pregnancy, are linked to ASD. Other environmental factors may also increase risk for ASD in those who are genetically vulnerable, though more research is needed on these factors. Childhood vaccination is not one of these environmental risk factors.
The consequences of measles, diphtheria, whooping cough, severe Covid-19 and other preventable infectious diseases can be catastrophic to an individual or a population and lead to death and long-term disability (as evidenced by recent outbreaks of measles in several countries). Research indicates that the lower the immunization rate in a population, the greater the risk of these preventable infections.
Vaccine hesitancy among parents and healthcare providers persists and appears to be on the rise in recent years. Internet searches regarding ASD and vaccines are increasingly frequent. Parents and some providers cite that concerns about ASD may contribute to this hesitancy despite the lack of supporting evidence in the peer-reviewed literature. Parents of children with ASD have higher rates of vaccine hesitancy, are less likely to have their children vaccinated, and are more likely to attribute their child’s ASD to vaccines compared to parents of children who do not have ASD. Thus, vaccine hesitancy is present despite robust evidence indicating that primarily genetic factors and possibly some environmental factors play a role in the pathogenesis of ASD.
To ensure that all children receive appropriate immunizations, the American Academy of Child and Adolescent Psychiatry recommends:
- All children and adolescents receive routine immunizations according to the current U.S. Centers for Disease Control and Prevention Advisory Committee on Immunization Practices Recommended Child and Adolescent Immunization Schedule, unless medically contraindicated.
- Prioritizing research on the potential causes of ASD, including possible environmental risk factors.
- Public education campaigns on the safety and efficacy of routine vaccinations and lack of evidence supporting any relationship between routine vaccines and the development of ASD.