viernes, 23 de mayo de 2014

CDC - Concerns About Autism - Antigens - Vaccine Safety

CDC - Concerns About Autism - Antigens - Vaccine Safety

Vaccines not associated with risk of autism

Group of kids

A new study evaluating parents’ concerns of “too many vaccines too soon” and autism has been published online in the Journal of Pediatrics Adobe PDF file [PDF - 256 KB]External Web Site Icon , March 29, 2013. It adds to the conclusion of a 2004External Web Site Iconcomprehensive review by the Institute of Medicine (IOM) that there is not a causal relationship between certain vaccine types and autism. The results provide relevant data for the current childhood immunization schedule.
The study looked at the amount of antigens from vaccines received on one day of vaccination and the amount of antigens from vaccines received in total during the first two years of life and found no connection to the development of autism spectrum disorder (ASD) in children. Antigens are substances in vaccines that cause the body’s immune system to produce antibodies to fight disease.
Researchers collected data from 3 managed care organizations in a group of 256 children with ASD compared with 752 children without ASD.
The study’s main findings report:
  • The total amount of antigens from vaccines received was the same between children with ASD and those that did not have ASD.
  • Children with ASD with regression (the loss of developmental skills during the second year of life) did not receive an increased number of vaccine antigens when compared to children without ASD with regression.
  • The number of vaccine antigens has decreased in recent years. Although the routine childhood vaccine immunization schedule in 2013 contains more vaccines than the schedule in the late 1990s, the maximum number of vaccine antigens that a child would be exposed to by 2 years of age in 2013 is 315, compared with several thousand in the late 1990s. This is due to changes in the vaccines. For example, the older whole cell pertussis vaccine causes the body to produce about 3,000 different antibodies, whereas the newer acellular pertussis vaccines cause the production of 6 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 that are not associated with vaccination. This study demonstrates that autism spectrum disorder is not associated with immunological stimulation from vaccines during the first 2 years of life.
Parents should expect the vaccines their children receive are safe and effective. CDC, along with other federal agencies, is committed to assuring the safety of vaccines through rigorous pre-licensure trials and post-licensure monitoring.

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