I know the survival rate for kids who've reached three or more is still near 100%. Under 3, I'm not so sure.
I think the first MMR is at about 12 months, then there are 2 more staggered at several year intervals. Most infants get some protection from their mothers antibodies if she has them
This of course leaves some infants very vulnerable, and the effect of rubella on the unborn babies of women who are pregnant and don’t realize it can be terrible- I remember this from the 1950’s
Measles was one of the diseases that had a lot to do with wiping out native Americans when the euros arrived
MMR’s first dose is between 12-15 months. Second dose is between age 4-6.