According to Wikipedia, plenty of US home schoolers are unprotected against measles. I'd reckon the same could be said of UK home educators. The hypothesised link between MMR and autism was the killer blow. Since plenty of families in the HE community contain children with autistic spectrum disorders, many younger siblings would not have been vaccinated. Other home educators just reject vaccination on principle.
In the population as a whole, the number of measles cases has shot up this year. There have already been over a thousand cases and this despite the fact that rate of vaccination in the younger age ranges has slowly risen, though it has apparently recently stalled. Herd immunity is only achieved when 95% of the population are vaccinated or are already immune.
A small percentage of those who have received two doses of the vaccine are still susceptible to measles, though they should have a less severe form of the disease.
Deaths from measles are due largely to an increased susceptibility to secondary bacterial and viral infections. Mortality rates in the developed world are quoted at best as being around 1/5000, (though other sources put it at 1/1000). However, even in the developed world, 30% of the immuno-compromised will die if infected. The mortality rates in undeveloped countries ranges from 5 - 10% and there is currently a huge push to vaccinate those most at risk in these populations, ie: the under fives.
Measles is highly contagious. Once it gets a grip, people will die or be left with permanent complications such as brain damage, however well-nourished they may be.
There is no proven link between autism and MMR. When they stopped using the vaccination in Yokohama, the incidence of autism continued to rise.
The single vaccine for measles result in more cases of life-threatening anaphylaxis.
Go get your MMR!