A special panel of the National Academy of Sciences has concluded that vaccines do not cause autism and urged scientists to turn to other avenues of research in an effort to understand the reasons for the increased incidence of the devastating disease.

Several well-designed studies have provided “overwhelming evidence” that neither the measles-mumps-rubella (MMR) vaccine nor the thimerosal preservatives used in some vaccines are associated with autism, said the committee’s chair, Dr. Marie McCormick of the Harvard School of Public Health.

“Most cases of autism result from events during the prenatal period or shortly after birth,” and those should be the focus of future efforts, she said.

Autism is a developmental disability caused by a brain abnormality in which children seem isolated from the world around them.