March 29, 2013
One In Ten Parents Still Believe Too Many Vaccines Cause Autism
Lawrence LeBlond for redOrbit.com - Your Universe Online
Despite all the scientific evidence that indicates vaccines do not cause autism, about 10 percent of parents still skip getting their children immunized for fear that the science is wrong. A growing number of parents are also forgoing vaccinations for their babies because they feel they are getting “too many shots, too soon.”
Many of these parents are subscribing to a false belief that not vaccinating their children is far safer than following guidelines set by the US Centers for Disease Control and Prevention (CDC). The primary concern is the number of vaccines that are administered either in a single day or over the course of the first two years of life.
A new study, published in The Journal of Pediatrics, has found that children who receive the full schedule of vaccinations have no increased risk of autism. Also, there is no link between receiving “too many vaccines” in a relatively short timeframe and risk of the neural disorder.
"This is a very important and reassuring study," Geraldine Dawson, chief science officer at Autism Speaks, who wasn't involved in the new paper, told USA TODAY´s Liz Zsabo.
"This study shows definitively that there is no connection between the number of vaccines that children receive in childhood, or the number of vaccines that children receive in one day, and autism," Dawson added.
For the study, Dr. Frank DeStefano and colleagues from the CDC and Abt Associates analyzed data from 256 children with autism spectrum disorder (ASD) and 752 children without ASD, born between 1994 and 1999; the children came from three managed care organizations.
DeStefano and his team looked at each child´s cumulative exposure to antigens (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 team determined the total antigen numbers by adding the number of different antigens in all vaccines each child received in a single day, as well as all vaccines each child received up to 2 years old.
DeStefano´s crew found that the total antigens from vaccines received by age 2, or the maximum received in a single day, was the same for both children with and without ASD.
Although the current vaccine schedule contains more vaccines than those in the late 1990s, the maximum number of antigens that a child is exposed to by 2 years of age today is 315, compared to several thousands in the late 1990s.
Because different types of vaccines contain different amounts of antigens, the research acknowledged that merely counting the number of vaccines received does not adequately account for total number of antigens received. For example, the older whole cell pertussis vaccine causes the production of some 3000 antibodies, whereas the newer acellular pertussis vaccine causes the production of only 6 or fewer different antibodies.
An infant´s immune system is capable of handling a large amount of immunologic stimuli and, from time of birth, infants are exposed to hundreds of viruses and countless antigens outside of vaccines.
“The possibility that immunological stimulation from vaccines during the first 1 or 2 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 said.
In 2004, a comprehensive review by the Institute of Medicine concluded that there is not a causal relationship between certain vaccine types and autism, and this study supports that conclusion.
Despite all the scientific evidence pointing to the efficacy of vaccines, myths continue to flourish, partly because researchers do not really know what causes autism, said Dawson. "Until we conduct the research to answer the questions about autism's causes and risk factors, parents will continue to have questions.”
Research increasingly suggests that many of the underlying changes that cause autism take place before birth, and even before conception. One recent study has also suggested that autism occurs when men decide to become fathers later in life, passing the genetic marker onto their kids, who then run a higher risk of producing autistic offspring.
Although symptoms of the disorder do not begin to appear until a child is 12 to 18 months old, Dawson and research partners have been able to pick up on subtle changes in eye and brain patterns as early as 6 months.
Though many parents may never believe vaccines are safe, the new study will probably be enough to reassure many others, said Karen Ernst of advocacy group Voices for Vaccines.
"Those who truly benefit from this article are the children of future parents," Ernst told USA TODAY. "These future parents will have more confidence in vaccinating their children on time. It is the job of parent-advocates like our members to speak up and make sure news about articles like this gets out."