MMR RISKS AND BENEFITS These are some of the general considerations, but I did not cover any of the controversy about MMR and autism, or any of the ingredients in the MMR vaccines. I will definitely dive into those studies with you later on! It’s important to know that the clinical trials for both brands (Priorix and MMR II) did not list the rates of serious adverse events in their subjects on the package insert. I had to look deep into the supplemental materials of one of the trials in order to