evidence: MMR vaccine [edit]The MMR vaccine as a cause of autism is one of the most extensively debated hypotheses regarding the origins of autism. Andrew Wakefield et al. reported a study of 12 children who had autism and bowel symptoms, in some cases reportedly with onset after MMR.[191] Although the paper, which was later retracted by the journal, concluded that there was no association between the MMR vaccine and autism, Wakefield nevertheless suggested a false notion during a 1998 press conference that giving children the vaccines in three separate doses would be safer than a single dose.[191][192] Administering the vaccines in three separate doses does not reduce the chance of adverse effects, and it increases the opportunity for infection by the two diseases not immunized against first.[8][10] In 2004, the interpretation of a causal link between MMR vaccine and autism was formally retracted by ten of Wakefield's twelve co-authors.[193] The retraction followed an investigation by The Sunday Times, which stated that Wakefield "acted dishonestly and irresponsibly".[194] The Centers for Disease Control and Prevention, the Institute of Medicine of the National Academy of Sciences, and the U.K. National Health Service have all concluded that there is no evidence of a link between the MMR vaccine and autism.[195][196][197]