It has been hypothesised that the MMR vaccine increases the risk of Crohn's disease, although the evidence for this is sparse. The study provides strong evidence against this theory and adds to the evidence that MMR vaccine is no less safe in this respect than the single measles vaccine.
Valerie Seagroatt, a statistician at Oxford University, analysed national data on hospital admissions for Crohn's disease in children and adolescents over the 12 years from April 1991 to March 2003.
She plotted rates for narrow (3-year) age bands and compared rates for those born before and after the introduction of the vaccine. She found no increase in Crohn's disease associated with the introduction of the MMR vaccination programme, providing strong evidence against the hypothesis that MMR vaccine increases the risk of Crohn's disease.