In 1998 Andrew Wakefield and 11 other co-authors published a study with the unremarkable title: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Such a title would hardly grab a science journalist’s attention, but the small study sparked widespread hysteria about a possible connection between the mumps-measles-rubella (MMR) vaccine and autism spectrum disorder (ASD).
The study itself has not stood the test of time. The results could not be replicated by other labs. A decade of subsequent research has sufficiently cleared the MMR vaccine of any connection to ASD. The lab used to search for measles virus in the guts of the study subjects has been shown to have used flawed techniques, resulting in false positives (from the Autism Omnibus testimony, and here is a quick summary). There does not appear to be any association between autism and a GI disorder.
But it’s OK to be wrong in science. There is no expectation that every potential finding will turn out to be true – in fact it is expected that most new finding will eventually be found to be false. That’s the nature of investigating the unknown. No harm no foul.