Unfortunately, evolution in action is, as ever, cruel and unpredictable. It’s perfectly possible that (especially given the difference in vulnerability between generic unvaccinated and immunocompromised or otherwise delicate cases) the bulk of the morbidity and mortality won’t even hit the children of those who chose not to vaccinate(not that this would be a terribly fair outcome unless the children also so chose); but a random set of others, with the carriers experiencing only minor cases.
At a population level, evolution may show trends in a given direction; but there’s a lot of noise involved, and being ‘noise’ is not a pleasant process for the individual.
