ArticlesAutism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association
Introduction
Wakefield and colleagues1 postulated that measles, mumps, and rubella (MMR) vaccination might be causally linked with autism. Although there is no scientific evidence to support this claim,2, 3, 4 neither are there robust data on the prevalence of autism in children born before and after the introduction of MMR vaccine to the UK in 1988. The postulated causal link between MMR vaccination and autism was based on a reported close temporal association between these two events.1 Since MMR vaccine is given at around 12–15 months of age and the mean age at which parents of children with autism first report concern about their child's development is 18–19 months,5 a close temporal association in some autistic children would be expected by chance.6
We undertook a population-based study in the North East Thames region to investigate trends in the incidence of autistic disorders before and after the introduction of MMR vaccine in October, 1988, and the immunisation histories of children with these disorders. We used case-series analysis methods to test for clustering of onsets within defined postvaccination periods.
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Patients and methods
Children with autistic disorders born since 1979 were identified in eight health districts in mid-1998 from computerised special needs/disability registers at child development centres and from records in special schools. Information on children with such disorders who were younger than 16 years of age was extracted from clinical records by one of three experienced paediatric registrars. The information extracted included the age at which the autistic disorder was diagnosed, the recorded age at
Results
498 children with autism were identified: 261 with typical (core) autism (prevalence rate in children under 16 years of age 5·3 per 10 000), 166 (3·4 per 10 000) with atypical autism, and 71 (1·4 per 10 000) with Asperger's syndrome· The diagnosis could be confirmed with ICD10 criteria, from information recorded in the clinical notes, in 214 (82%) cases of core autism, 52 (31%) cases of atypical autism, and 27 (38%) cases of Asperger's syndrome. 441 (89%) children were documented as having been
Discussion
Vaccination and vaccine safety are issues of major concern to the public, their elected representatives, and all health-care workers. Possible adverse reactions to vaccines have a particular attraction to various pressure groups and to the media, with important, and possibly catastrophic, effects on - public confidence - in immunisations and on vaccine uptake.10 The study by Wakefield and others1 and earlier work from those investigators suggesting an association between measles-containing
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