I think having a small percentage of the population who are anti-vax adds to the robustness of the species. What if, odds unlikely, that there was some proble

I think having a small percentage of the population who are anti-vax adds to the robustness of the species. What if, odds unlikely, that there was some problem with the vax where it killed or sterilized everyone who got it? It would be extinction except for the anti-vaxxers. Now this is an super unlikely event, but there's a non-zero chance this could happen.