RFK Jr. says cause of autism will be found by September, but experts fear he's reviving debunked theories

The nation's top health agency will undertake a "massive testing and research effort" to determine the cause of autism, Health and Human Services Secretary Robert F. Kennedy Jr. announced Thursday.

Kennedy, a longtime vaccine critic who has pushed a discredited theory that routine childhood shots cause the developmental disability, said the effort will be completed by September and involve hundreds of scientists. He shared the plans with President Donald Trump during a televised Cabinet meeting.

Trump suggested that vaccines could be to blame for autism rates, although decades of research have concluded there is no link between the two.