Parents would not be legally allowed to deny vaccinating their children
NOTE: The last measles death in the United States occurred in 2015
Nowadays, due to the vastly improved nutrition and hygiene, compared to the mid-19th century when large numbers of children died with measles because (due to under-nutrition) their livers were not adequately developed, measles has become a mostly two day event causing little stress to the child provided that the measles is allowed to proceed at its intended age.
Parents will note that their children have gone through a major emotional development and become much more balanced as well as finally getting their own faces.
In some Third World countries, such as Bangladesh, where chronic under-nutrition, as in 19th century Europe, is still rife, considerable numbers of children die because their livers are not adequately developed for the measles process, thus adding further support to the postulate expressed here.