A major U.S. study provides more evidence that there is no connection between the childhood vaccine for measles, mumps and rubella and autism in children.
The research puts another nail in the coffin of false studies published 17 years ago that led to a drop in immunization rates and, in turn, a rise in outbreaks of measles in Europe and North America.
The new study, released April 21, involved 96,000 children and found rates of autism were no higher among children who received the measles-mumps rubella (MMR) vaccine and those who were unvaccinated. It was published in the Journal of the American Medical Association (JAMA).
Researchers reported the same results among children who had an older sibling with autism — which put them at greater risk of developing the neurological disorder. They used detailed information from a health insurance database.
“These findings indicate no harmful association between MMR vaccine receipt and ASD (autism spectrum disorder) even among children already at a higher risk for ASD,” wrote the authors, led by Dr. Anjali Jain, pediatrician and vice-president at health-care consultant The Lewin Group in Virginia.
The study is the latest among a dozen papers showing that neither the age of onset of autism nor the severity of the condition differs between vaccinated and unvaccinated children, notes an accompanying JAMA editorial by Dr. Bryan King of Seattle Children’s Hospital.
“Controversy seems to follow autism like the tail on a kite,” he writes.
Although “the evidence is already abundant” that no connection exists between MMR and autism in children, immunization rates are low in certain regions because of this “inappropriate belief.”
That belief stems largely from fraudulent claims by British researcher Andrew Wakefield in 1998, which have since been discredited, and celebrities who have publicly perpetuated the idea.
Whether the new JAMA research will put to rest simmering uncertainty among some parents remains to be seen, says Dr. Natasha Crowcroft, chief of applied immunization research at Public Health Ontario and associate professor of public health at University of Toronto.
“The idea has a life of its own,” she said in an interview. “I think we could carry on doing brilliant research in the years to come, and the idea would still be out there. I don’t think research is going to be the thing that gets rid of it.”
She says that money and energy would now be better spent on helping children with autism and their parents, and investigating possible causes.
While most Ontario parents continue to have their kids immunized according to guidelines, which call for one dose of MMR after a child’s first birthday and a second at between 4 and 6 years of age, some remain torn and hold off.
Public Health Ontario has reported that childhood vaccination rates are below the benchmarks necessary to build herd immunity that protects the public from infectious diseases. Earlier this year, C. D. Howe Institute echoed those findings, and said Ontario kids are six percentage points short of the target for MMR immunization.
Those rates were blamed for measles cases that popped up in Toronto this year, following major outbreaks in California and other parts of the U.S.
A recent online survey of Ontario parents’ attitudes to immunization revealed that fears about autism were still a factor. The survey, completed in late 2013 and early 2014 as part of a research project on vaccine hesitancy, was led by Jordan Tustin, assistant professor at Ryerson University.
More than one in five of the 1,097 parents who responded reported their youngest child was not up to date with vaccinations. Of those, 20 per cent cited concerns over autism or other risks as factors.