M.D.
We live in NJ, they do require 2nd MMR shot or titers to prove immnity.
Both my girls did not receive their 2nd MMR shot, I had their titers done before they started Kindergarten and they both had immunity. Right before 2nd grade I had the titers tested again, still immune. Doctor said she can't say if they will or will not ever need a second shot. Something I will have to follow up on every few years. I would rather do that then give my daughter a shot for something they already have immunity to. If their immunity every becomes low, I would absolutely give them the second booster. But not until that time.
One of the reasons is because when I was 10 yrs old I got the chicken pox, I had such a mild case. 5 dots on my tummy, and I was out riding my bike because I felt fine. After I had my first child they asked me if I ever had, I told them how mild it was, he said I might not have immunity to it and might need to get a shot. I had my titers tested, and I was immune. These doctors like to just follow the recommended list and not test for titers because some people will not follow up every fews years.