You cannot reason a person out of a position he did not reason himself into in the first place. No amount of talking sense will change the course we are on because we are following a predetermined plan. It’s not rational or science based.
Why do so many people want to disprove the seriousness of an illness just because it affects their daily lives for a bit? That said, the more sterile we've become, the less resistance we have to illnesses. But they do exist and they do kill people.