A medicine, through natural selection, pushes a population of virus or bacterias to modify themselves in order to live. In a long term, it can be a serious problem, since, with no intention, we may end up being responsible for the appearance of a super germ, resistant to any medicine we already know.
Paul Ewald proposes a different approach in this "humans versus diseases war". The idea is to use this very same evolutive principles to push a change to make a virus or bacteria harmless to humans.
Check the video, it is worth to watch.