Compulsory MMR vaccination?

[PBI]

I think if they are offered and given in schools, then people will just get them anyway. Usually there's one kid in the class who doesn't because their parents didn't want them to, but that doesn't pose a serious health risk (or does it, I have no idea)?

As I understand it, one of the aims of vaccination is to ensure that enough of the population have been vaccinated to ensure that the if one person does contract the disease, they will on average infect less than one other person, so it will not spread widely and become an epidemic. As I understand it, there is generally a fairly clearly defined cutoff percentage below which the disease will almost always spread throughout the unvaccinated population, and above which it will not be able to spread widely, so that the few people who aren't vaccinated will be effectively protected by those who are. Thus it's not a problem if only a few people are unvaccinated, but if large numbers are unvaccinated (as with MMR) it's possible for the disease to spread among them. I don't know the exact number for measles, although I believe they are generally in the 90%ish range. Almost certainly more than 75%.

The problem though with giving the vaccine at school, is that then anyone under the age of 5 is unprotected. Doesn't measles most often affect kids under that age?