During 5,025,754 person-years of follow-up, comparing MMR-vaccinated with MMR-unvaccinated children yielded an adjusted autism hazard ratio of 0.93 (95% CI 0.85 to 1.02). Similarly, no increased risk for autism after MMR vaccination was consistently observed in subgroups of children defined according to sibling history of autism, autism risk factors (based on a disease risk score) or other childhood vaccinations, or during specified time periods after vaccination.
In a related editorial, the authors discuss the findings of this study, highlighting that it adds to previous studies through significant additional statistical power and by addressing the hypotheses of susceptible subgroups and clustering of cases. The authors however note the resistance from the public, in accepting new facts in relation to the lack of association between the MMR vaccine and autism, and highlight that new ways of communicating the evidence are warranted.