Heard from other mums that in my part of west london because so few children are being given the MMR that its effectiveness is reduced. So once you get your MMR at 13 months then they want you to get a booster at 18 months instead of 3-5 years old. My DD had to have hers in the hospital last week at 16 months (egg allergy) no mention by the nurse of the booster. Surely this is unnecessary and experimenting with children without knowing the impact of two MMRs so close together. Even if its less effective even if DD gets measles she will have some immunity and not get the serious measles side effects. Im going to refuse the booster until she is 4 or 5, poor DD has been ill ever since her MMR last week.