MMR shot began reacting extremely odd and completely regressed within several days and is diagnosed with a severe form of autism. Coincidence? Probably not. he unfortunately was just one of those unlucky enough to be genetically predisposed to having a reaction to the vaccination unlike others. We vaccinate our children for the purpose of helping them avoid diseases that have been eradicated in the western world however as I see it and I think this is how my sister sees it some people will have an adverse reaction. No shot or pill or medicine of any kind will be 100% foolproof and will work equally well on everyone. We have to get beyond this idea that somehow medicine and science have discovered the cure-all when it really is possibly a cure most at best. DNA is a tricky thing and we are still in the formative stages of understanding it.