The scientific evidence does not support a causal link between the MMR vaccine and autism, according to Professor Michael Absoud, Professor of Paediatric Neurodevelopmental Disability at King's College London.
Professor Absoud stated that large population studies and systematic reviews involving millions of children have found no increased risk of autism after MMR vaccination. He explained that the first dose of the MMR vaccine is given around the same age when early autistic differences may become apparent to parents, leading to a temporal association that is not causation.
The original 1998 Lancet paper that suggested a link between MMR, bowel symptoms, and autism was based on a small, highly selected sample. This paper was later retracted due to serious scientific and ethical failings. Subsequent epidemiological studies have not found that MMR causes autism.
Professor Absoud also noted that the increase in autism diagnoses is best understood as reflecting broader diagnostic criteria, greater awareness, and improved recognition, rather than vaccines. He added that autism is a complex neurodevelopmental condition with strong genetic contributions and is not explained by a single postnatal exposure like MMR.
While vaccines can have side effects, serious adverse reactions to MMR are very rare, and the risks of measles, mumps, and rubella are substantially greater. Measles, for instance, is highly infectious and can lead to pneumonia, encephalitis, long-term disability, and death. Splitting the MMR into separate vaccines is not supported by evidence as being safer or better and could leave children unprotected for longer.