aspect of how their choices can impact others, but at a minimum virtually all of them at least understand that vaccines have enormously reduced the incidence of countless terrible diseases, so much that it is possible for them to consider not vaccinating. Those that then elect to not vaccinate are choosing to not participate in a massive social good because they are relying on everyone else to do it for them. Virtually everyone understands at least that much, and that is an incredibly selfish position to take. If they also understand the impact their decision has on those in society who are even more vulnerable (such as the OP's wife) then that makes them even more selfish, but not understanding that doesn't mean that they are not selfish.