This is kinda retarded. The original measles vaccine was tested against placebo. The updated MMR was compared against groups getting the original component shots separately. They use active controls for shit they are updating. It’s considered unethical to give children a saline shot when their parents think they are getting a vaccine. The famous 13 studies claim are a great example of sample bias and poor methodology, and just not being aware when a study author tells you their data is bad.