Further MMR drop-in clinics are being held in the Swansea area today, but Public Health Wales says there are concerns the outbreak is spreading.
More than 43,000 non-routine MMR vaccinations have been given since the start of the outbreak in November.
But health chiefs say 38,000 children are still unvaccinated across Wales and there is potential for further outbreaks.
Four clinics are being held today at Singleton and Morriston Hospitals in Swansea, the Princess of Wales Hospital in Bridgend and Neath Port Talbot Hospital between 10am and 4pm.
A further clinic is being held at the Royal Gwent Hospital in Newport next Saturday (18th May) between 11am and 3pm.