Second immunisation has not affected incidence in England

EDITOR—Metcalf concludes that the scientific evidence does not support a causal link between measles virus and Crohn's disease.1 Though few readers of the BMJ are likely to disagree with her appraisal of the science, parental concern about the safety of the vaccine remains high fuelled by continuing media interest in this controversial topic. More worrying is the recent decline in MMR vaccine coverage2 and evidence which suggests that most practice nurses would not give their own child a second dose of MMR vaccine because of concerns about vaccine safety.3

One of the claims made by the leading proponent of the hypothesis that measles vaccine causes Crohn's disease is that there has been a “dramatic escalation” in paediatric cases in the wake of the 1994 national measles-rubella vaccination campaign targeted at school aged children.4 We have monitored hospital discharge diagnoses for Crohn's disease (ICD-9 code 555 until March 1995, ICD-10 code K55 from April 1995) in children aged 5-16 years before and after the campaign using computerised hospital episode statistics from all districts in England (figure). Children with new cases of Crohn's disease are almost always admitted to hospital, and this is a well …