Vaccines can be prophylactic ( example : to prevent or ameliorate the effects of a future infection by any natural or `` wild '' pathogen ) , or therapeutic ( e.g. , vaccines against cancer are also being investigated ; see cancer vaccine ) .
Vaccines can be prophylactic ( e.g. to make the effects of a future infection by any natural pathogen less dangerous or stop them completely ) , or therapeutic ( e.g. vaccines against cancer ) .