Health Science Reviews

by Sedzani Mbedzi

Autism spectrum disorder (ASD) is a developmental disability that can cause significant social, communication and behavioral challenges. The Centers for Disease Control and Prevention (CDC) is the national agency for US that is committed to providing essential data on ASD, searching for factors that put children at risk for ASD and developing resources that help identify children with ASD as early as possible.

Due to the continual emergence and re-emergence of viral disease that results in epidemics and pandemics, vaccines are needed to mitigate the spread of infections. However, there is persistent parental refusal of vaccines due to fear that they cause autism in children. As such three specific hypothesis have been proposed.

1. The combination measles mumps rubella (MMR) vaccine causes autism by damaging intestinal lining which allows the entrance of encephalopathic proteins.
2. Thimerosal an enthylmecury containing preservative in some vaccines is toxic to the central nervous system.
3. The simultaneous multiple administration of multiple vaccines overwhelms or weakens the immune system

In this study researchers from CDC ASD set out to answer the following questions:

1. Do vaccines cause autism spectrum disorder?
2. Is there an ASD epidemic?
3. Can adults be diagnosed with ASD?
4. Is increasing exposure to antibody stimulating proteins and polysaccharides in vaccines associated with risk of autism?

Centers for disease and communication Autism and developmental monitoring network revealed that about 1 in 54 children have been identified with ASD in communities in the United States. ASD occurs in all racial, ethnic and socioeconomic groups. It is more common in boys than boys. A leading researcher in South Africa based in Cape town estimates that about 2% of the population is affected with ASD, however this is currently not reliable due to lack of access to medical interventions and cultural miscerptions.

Methods followed to answer the question

This study was a continuation of previous study. Researcher’s analyzed data from a case-control study conducted in 3 managed care organizations (MCOs) of 256 children with ASD and 752 control children in a matched birth year, sex, and MCO group. They further evaluated the associations between the total cumulative exposure to antibody stimulating proteins and polysaccharides from childhood vaccinations and 3 outcomes: ASD, autistic disorder (AD), and ASD with regression. They also evaluated associations with the maximum number of antigens to which a child was exposed in a single day. Potential confounding factors were ascertained from parent interviews and medical charts.

Major findings

More than 10% of parents of young children refused or delayed vaccinations, with most believing that delaying vaccination is safer than providing them in accordance with the CDC recommended vaccination schedule. There was no evidence of harm caused by the low doses of thimerosal (ingredient in vaccine), except for minor reactions like redness and swelling at the injection site.  There was no evidence of an association between exposure to antibody-stimulating proteins and polysaccharides contained in vaccines during the first 2 years of life and the risk of acquiring ASD, AD, or ASD with regression.

Conclusion

The study by Stefano and co-workers concluded that vaccines do not cause ASD, some of ASD cases could be a result of socio economic factors and could be due to the fact that the infant’s immune system is capable of responding to a large number of immunologic stimuli.

References

DeStefano, F., Price, C.S. and Weintraub, E.S., 2013. Increasing exposure to antibody-stimulating proteins and polysaccharides in vaccines is not associated with risk of autism. The Journal of pediatrics, 163(2), pp.561-567.

McCarthy, M., 2014. Autism diagnoses in the US rise by 30%, CDC reports. BMJ: British Medical Journal (Online), 348.