Firgures from Abertawe Bro Morgannwg University Health Board show that more than 10% of children aged 11 to 16 in Swansea have not had both MMR vaccinations.
The number of children unvaccinated in Monmouthshire are also higher than the all-Wales average. More than 15% of children aged between 11 and 18 years old have not received both MMR vaccines.
More children in Powys, Newport, Ceredigion and Pembrokeshire have unvaccinated than the national average.
2013 is expected to be the worst year for measles in the UK for the past two decades. Read more about the illness and how it is treated.
If the Government's top adviser on immunisation thinks the risk of an emergency in England is a possibility, I believe him.