92 has hit it with "herd immunity." For vaccines to be effective for highly infectious diseases, the vaccination rate needs to be very high, around 95% for measles. Measles is so contagious, that the air in a room is considered unsafe for two hours, after someone with measles has only breathed in it. Fomite (surface) contamination lasts even longer. That is the reason for mandatory childhood vaccination. There are have always been safeguards allowing leniency for kids like CA's, and always will be, with doctor's excuse. Otherwise, it simply can't be a matter of personal choice, when that choice may endanger thousands of others. My freedom ends exactly where it starts to impinge on endangering yours...