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New study finds no link between vaccines and autism

A US study tries to dispel parents’ fears about ‘too many vaccines’.

Image: Autism Young Child Image via Shutterstock

A NEWLY-PUBLISHED study has refuted American parents’ fears that giving children “too many vaccines too soon” causes autism.

Researchers concluded that there is no association between vaccines and the disorder. In the US, many parents have expressed concern at how and when vaccinations are administered. Much has been written about the number of vaccines administered, both on a single day and cumulatively over the first two years of life.

Although scientific evidence suggests that vaccines do not cause autism, about one-third of parents continue to express concern that they do; nearly one in 10 parents refuse or delay vaccinations because they believe it is safer than following the Centers for Disease Control and Prevention’s (CDC) schedule.

The study, due to be published in the Journal of Pediatrics, analysed data from 256 children with autism spectrum disorder (ASD) and 752 children without ASD.

Dr. Frank DeStefano and colleagues from the CDC and Abt Associates looked at each child’s cumulative exposure to antigens, the substances in vaccines that cause the body’s immune system to produce antibodies to fight disease, and the maximum number of antigens each child received in a single day of vaccination.

The authors found that the total antigens from vaccines received by age two, or the maximum number received on a single day, was the same between children with and without ASD. When comparing antigen numbers, no relationship was found when they evaluated the sub-categories of autistic disorder and ASD with regression.

Although the current routine childhood vaccine schedule contains more vaccines than the schedule in the late 1990s, the maximum number of antigens that a child could be exposed to by 2 years of age in 2013 is 315, compared with several thousand in the late 1990s. Because different types of vaccines contain varying amounts of antigens, the research acknowledged that merely counting the number of vaccines received does not adequately account for how different vaccines and vaccine combinations stimulate the immune system. For example, the older whole cell pertussis vaccine causes the production of about 3000 different antibodies, whereas the newer acellular pertussis vaccine causes the production of six or fewer different antibodies.

An infant’s immune system is capable of responding to a large amount of immunologic stimuli and, from time of birth, infants are exposed to hundreds of viruses and countless antigens outside of vaccination.

According to the authors, “The possibility that immunological stimulation from vaccines during the first one or two years of life could be related to the development of ASD is not well-supported by what is known about the neurobiology of ASDs.”

In 2004, a comprehensive review by the Institute of Medicine concluded that there is no causal relationship between certain vaccine types and autism, a conclusion supported by the new study.

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