Again if you and your kid is vaccinated already you have zero worry about shedding that’s why you take the MMR in the first place. It’s not rocket science , if you are not vaccinated to MMR you are the only ones at risk of getting it. Especially after boosters into adulthood.
I understand the value of vaccines. I disagree with the manner of modern day implementation. There were fewer vaccines and they were spread out when I was young. There are crap "vaxxines" now like the COVID disaster. My background in molecular biology and pathogenic microbiology inclines me to favor the attenuated pathogen/antigen over the mRNA approach.