Autism-Vaccine Link: Evidence Doesn't Dispel Doubts
Many major medical groups say vaccines don't cause autism. Many parents say they do. So who's right?
Vaccines and Autism: Other Studies Under Way continued...
The Childhood Autism Risks From Genetics and the Environment (CHARGE) study is under way at the University of California, Davis. Funded by the National Institute of Environmental Health Sciences and enrolling more than 600 families with autism, this study is looking at the interplay between genetic and a wide range of environmental factors in autism. Vaccines are one of the many environmental factors being analyzed.
In addition, the CDC's Centers for Autism and Developmental Disabilities Research and Epidemiology network (CADDRE) is collecting data on environmental risk factors, including vaccines, that might put children at risk of autism.
Using the same environmental-factor checklist as CHARGE and CADDRE, the NIMH is looking at differences between children with regressive autism and children with more classic forms of autism.
"We are looking at differences in environmental exposures, including vaccines but also including things like older brothers who had a cold and mothers who drank a lot of diet soda during pregnancy," Swedo says.
The CDC and the NIH are also performing epidemiologic studies in Norway and Denmark to expand previous research into whether vaccinated children have any more autism than unvaccinated children.
"Neither [NIMH Director Tom] Insel or I are ready to discard the vaccine hypothesis, but we don't think there is anything in vaccines that causes autism in the vast majority of cases," Swedo tells WebMD. "In earlier cases where vaccines caused rare complications, we figured it out quickly. Since vaccines are given so often, if there was a strong connection between vaccination and autism we would know it by now. What we are not discarding is the one-in-ten-thousand or one-in-a-million cases that might have a link."
Vaccines and Autism: High Stakes
The specter of autism frightens parents. But today few parents in the U.S. or other developed countries have seen the suffering and death wrought by measles and other disease that vaccines can prevent, including measles, tetanus, polio, diphtheria, whooping cough, and influenza. These diseases still afflict millions of children in places that vaccines don't reach.
Every year, 2.5 million unvaccinated children worldwide die of diseases that vaccines could have prevented, and vaccines prevent the deaths of an additional 2 million children, according to the World Health Organization.