Beyond serious in adults. Fairly high incidence of very painful inflammation of gonadal tissue and fairly high incidence of sterility developing. Have to blame this sort of thing, as well as the resurgence of whooping cough, on all those who profess avoiding immunizations. Although there are always risks of some immunizations, you have to weigh the risks and sequellae of the diseases. I am a very conservative physician and there are indeed some shots and medications i would advise against, but I do not think any adult wants to suffer some of these childhood diseases at an advanced age. Generations of not having to deal with measles, mumps, German measles, chickenpox, bordatella, etc have led to a complacency as many do not realize how devastating these things were in the past and could be again.