I had the measles as a 4yo child and there was a big development boost after the illness passed, I even teached myself how to write before I got to school. It was a time when "measles partys" weren't uncommon. On a "measles party" there was one child with measles inviting all the kids from the neighbourhood and the parents encouraged us to all drink out of the same cup. It was made up as a game for the children back then. Interesting is that at those partys not all the children got infected, the case was mostly that only a few got infected. It were probably the kids with a lack of vitamin A that were at the highest risk to get infected. To just get the measles and cure it at home with cold calf wraps and high dosage of vitamin A was recommended by the doctor rather than vaccinating a healthy child, since that could do more damage than being useful. Vaccination is only reasonable for childern born with already weak immune system. You can get the measles only once in a lifetime and when you got it then you are immune to it for the rest of your life, you can even expand that immune defense with inheriting it to your offspring as a woman. A vaccined woman can't do that since there aren't real antibodies in her blood stream, plus she still can get the measles and transfer it to others even if it doesn't break out in herself.