Taking my 4 year old ds for his first mmr jab at 2pm. I am feared to death! Have thought about it alot which is why he's having it at the age of 4. Has anyone elses child had it later and were they o.k? My son has had a poor response to other vaccinations (hasn't made the antibodies) and he has low immunoglobulins in his blood so i have been advised that he should have it. Just hope i've made the right descision!