The number of cases of measles in an outbreak centred on the Swansea area have now reached 620.
Public Health Wales say there is 'no sign of the outbreak coming to an end' despite more than 1,700 children receiving the MMR vaccination over the weekend.
At least 6,000 children remain unvaccinated in the county of Swansea and parents are being urged to ensure that all children receive the two doses of the MMR vaccine needed to provide protection against measles.
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.