While it is true that vaccines are an entity that helps the body to form antibodies to some diseases, it is prudent to say that we are talking about pathogens with a life of their own that can mutate and create resistance to antibodies and although the scope of the tests has not been scientifically proven. vaccines is also prudent to admit that medicine was made to prevent and not cure, hence the importance of keeping the studies up to date, taking into account the population advance of the world, excellent publication very complete and excellently reasoned @barrydutton