In the latest study to examine the association between childhood vaccines and autism, researchers found no link between autism and the number and timing of vaccinations.
Frank DeStefano, MD, MPH, and colleagues from the Centers for Disease Control and Prevention and Abt Associates Inc. analyzed data from 256 children with autism spectrum disorder and 752 children without ASD (born between 1994 and 1999) from three managed care organizations. They looked at each childs cumulative exposure to antigens and the maximum number of antigens each child received in a single day of vaccination.
In a study published March 29 on the website of the Journal of Pediatrics, researchers determined the total antigen numbers by adding the number of different antigens in all vaccines each child received in a day and all vaccines each child received up to age 2.
The authors found that the total antigens from vaccines received by age 2 and the maximum number received on a single day were the same between children with and without ASD. Furthermore, when the researchers compared antigen numbers, no relationship was found when evaluating 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 age 2 in 2013 is 315, compared with several thousand in the late 1990s. Because different types of vaccines contain varying amounts of antigens, this 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 3,000 different antibodies, whereas the newer acellular pertussis vaccine causes the production of six or fewer different antibodies, the researchers noted.
An infants 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, the researchers noted. “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,” the authors wrote.
In 2004, a comprehensive review by the Institute of Medicine concluded that there is not a causal relationship between certain vaccine types and autism. This study supports that conclusion, the authors said.
A PDF of the study is available at www.jpeds.com/webfiles/images/journals/ympd/JPEDSDeStefano.pdf.