Um... since it takes a minimum of 10-12 years of clinical testing on thousands of volunteers before a vaccine can even be submitted for FDA approval, don't you think that any vaccine candidate that "plays havoc with the immune system" would be weeded out fairly early in the process?
No, because it can take much time for such effects to occur, and they masquerade as other things, mostly inflammatory ailments. It's very difficult to correlate, for example, a child developing asthma, with a vaccination he may have received years before, or the death of a senior citizen from pneumonia he caught when his immune system was weakened by the natural effects of a flu inoculation.
The veterinary profession has gotten wise about the potential hazards of vaccination, and I think it's time the human medical profession caught on too.