Humanity is as successful as it is today because we take care of our weak, not because we destroy them. You are confusing evolution through natural selection with eugenics...
This deserves its own reply. No, it's you who are confusing the two.
Eugenics is when people choose who should live and who should die. This is abhorrent, for a variety of good reasons. It's not only morally repugnant, but from an objective point of view, it is detrimental to the species because when you kill those who are different from you, you also kill the good mutations, i.e. those who are fitter than you.
Natural selection is when those who survive due to their own abilities have more viable offspring, causing a propagation of successful genes and mutations, not selected genes.
If anything, vaccination is more like eugenics than anti-vaccination is. Money and culture controls who gets vaccinated and who doesn't, and most people want their own children to have an advantage, even if unfair.