If the ppl are vaccinated, those ppl should be safe, and in theory those unvaccinated masses dying off from X illness increases the overall fitness of the population.
However, it's not at all about that. This is about forcing those who may not think or believe the same to not only acquiesce, but to actively proclaim they are science deniers and that another group is infallible and correct.
I'm not an anti-vaxxer per-se, i think vaccines for things such as polio, mmr are important. But i don't think others such as flu and possibly hpv are worth the risk.
I don't support forced vaccination however, and the more those who loudly tout forced vaccinations the more it leads me to believe that there may be credibility issues with the vaccine efficacy and the vaccination's research.