My kids got it twice!
Once when they were under a year old, not too serious a case.
Then again when they were about three. Apparently the immune system isn’t fully mature when they are babies.
One of my kids came up to me, point to his arm, and said, “I have a ‘chicken pock’.” It turned out he was correct!
My kids were vaccinated but 2 out of 3 got very mild cases of the “chicken pops.” They weren’t nearly as miserable as Hubs and I when we were kids and got all the childhood illnesses.