> Shouldn't a disease only spread to unvaccinated people? Yes, and there are, by necessity and previously discussed, always going to be some unvaccinated peopl

> Shouldn't a disease only spread to unvaccinated people? Yes, and there are, by necessity and previously discussed, always going to be some unvaccinated people. In some cases this is because the vaccine cannot be administered until a certain age. In some cases, it is because the vaccine fails. A small amount of "free riders" can work. It is when parents put too many free riders into a population that it crosses a tipping point.