Summary of findings 10. Safety: inflammatory bowel disease.

Safety: inflammatory bowel disease
Patient or population: children 9 months to 15 years old Setting: general population Intervention: MMR vaccine Comparison: unvaccinated
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)
	Risk of IBD amongst unvaccinated	Risk of IBD amongst vaccinated
Case control ‐ all IBD, MMR	Study population		OR 1.42 (0.93 to 2.16)	409 cases, 1416 controls (3 observational studies)	⊕⊕⊕⊝ MODERATE1
	0 per 1000	0 per 1000 (0 to 0)
Case control ‐ ulcerative colitis, MMR	Study population		OR 1.35 (0.81 to 2.23)	292 cases, 582 controls (2 observational studies)	⊕⊕⊕⊝ MODERATE1
	0 per 1000	0 per 1000 (0 to 0)
Case control ‐ Crohn's disease, MMR	Study population		OR 0.64 (0.42 to 0.98)	514 cases, 804 controls (3 observational studies)	⊕⊕⊕⊝ MODERATE1
	0 per 1000	0 per 1000 (0 to 0)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IBD: inflammatory bowel disease; MMR: measles, mumps, rubella vaccine; OR: odds ratio
GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

¹Upgraded one level due to residual confounding ‐ confounding expected to increase the effect but no effect was observed.