My son is now 12 years old. In 2000, you will no doubt recall that things kicked off with the MMR controversy - so we elected to have singles. All was well and fine - until the mumps single (mumpsvax) went out of production. DS has had singles x 2 for all of the diseases/ illnesses except mumps for which he has just had one jab. Not sure what to do. Mumps is the one which can be a risk to boys/men's fertility. Will I really have to concede defeat and give him the MMR? Has anyone in this prediccament resolved this otherwise ? How does the blood test work ? Does anyone know whether they will make the single mumpvax again ? Really anxious as my DS is fast approaching puberty.