Vaccines are clearly not the reason children develop autism. So what is? There is strong evidence that genetics play a role, and that defects in the brain of children on the autism spectrum occur during pregnancy. Exposure during early pregnancy to particular chemicals in the environment or infections could be involved. Researchers have suggested that damage could be done by the drugs thalidomide, misoprostol and valproic acid; by exposure to the insecticide chlorpyrifos; and by infection of the mother with the rubella virus.

This is what we need to be focusing on, not the myth that vaccines cause autism. Yet I fear that such myths will be used to justify new rounds of hearings or unwarranted investigations of federal agencies, including the C.D.C. This would only distract attention from these agencies’ crucial work, and the real needs of families with children on the autism spectrum, such as mental health services, work-entry programs for adults and support for the research being done by the National Institutes of Health.

Today, parents in Texas have to live in fear that something as simple as a trip to the mall or the library could expose their babies to measles and that a broader outbreak could occur. Perpetuating phony theories about vaccines and autism isn’t going to help them — and it’s not going to help children on the autism spectrum, either.