Autism risk isn’t increased by the use of recommended childhood vaccines, U.S. health officials found in a study addressing parent concerns that too many immunizations may cause the disorder.
An analysis of 1,000 toddlers showed no differences in exposures to vaccines between autistic and normally-developing children, according to findings published in the Journal of Pediatrics by researchers at the Centers for Disease Control and Prevention in Atlanta. The CDC recommends 10 immunizations before age 2, and some require more than one shot.
Multiple studies have shown measles, mumps and rubella vaccines don’t individually cause autism. A third of parents surveyed in a previous report were concerned too many vaccines given before age 2, or on the same visit, may be a contributor. About 1 in 10 toddler parents refuse or delay vaccinations because they believe the schedule to be unsafe, the study said.
“This is a very important and reassuring study,” said Geri Dawson, the chief scientific officer of Autism Speaks, an advocacy organization, in a telephone interview. She wasn’t involved in the study. “It’s going to be very helpful in addressing some of the concerns parents have had about vaccination schedules.”
The research compared data taken from managed-care groups for 256 children with autism and 752 without. It found no differences in the amount of antigens the kids were exposed to in the first 2 years of life. It also found no support for the idea that too many vaccines on one doctor’s visit might increase the risk of autism.
Antigens are substances in vaccines that cause the immune system to create antibodies. Some people have suggested that these immune-stimulating proteins hurt children’s developing bodies if too many are administered too quickly.
“This adds more weight to the evidence that vaccines don’t cause autism,” said Frank DeStefano, a study author and the director of immunization safety office at the Atlanta-based CDC, in a telephone interview.
Vaccines were singled out by parents in part because of a 1998 study by Andrew Wakefield at the Royal Free Hospital in London published by the Lancet. That study was retracted in 2010, and was determined to be fraudulent, according to a report in the Lancet in January 2011.
The vaccine link seemed convincing to parents because some autistic children develop normally over their first year of life and then regress, losing their skills, Dawson said. That happens in about a quarter of autistic people.
“It’s understandable that parents think about what could cause this regression to happen and vaccines were one question,” Dawson said.
Today’s study looked at a subset of children who also experienced the regression, and found no differences there either.
“Vaccinations have been one of the most successful public health interventions of the past 100 to 200 years,” DeStefano said, noting the eradication of polio and other once-common childhood illnesses from the U.S. “Delaying or not vaccinating exposes a child to potentially life-threatening disease.”