The number of cases in the Swansea measles epidemic has risen to 1,039, an increase of 28 in the past two days.
Public Health Wales (PHW) said across Wales the total has reached 1,170, and 85 people have been hospitalised.
It said that 33,000 non-routine MMR vaccinations have been given around the country during the outbreak.
But it said that too few 10-18-year-olds were receiving the jab, and they were the hardest hit by the epidemic.
Large numbers of children in that age group were never given the MMR vaccine, the result of a scare that caused panic among parents.
It followed research by Dr Andrew Wakefield in the late 1990s which linked the vaccine with autism and bowel disease.
His report, which was published in The Lancet medical journal, was later discredited, with health officials insisting the vaccine was completely safe.
But PHW said it was concerned that many of those children were still unvaccinated and urged their parents to ensure they now received the jab.
Of the 33,000 non-routine vaccinations given across Wales during the outbreak, only about 8,000 of those were in the 10-18 age group. This still leaves almost 43,000 unvaccinated.
Wales measles map – April 2013 This series of maps shows how suspected measles cases have increased between November 2012 and April 2013. Each case represents a doctor’s diagnosis and is not laboratory confirmed.
Dr Marion Lyons, director of health protection for PHW, said: “The efforts to vaccinate susceptible young people children across Wales have been excellent, with non-routine vaccinations being given in their thousands by GPs, in schools and in emergency drop-in clinics.
“This undoubtedly will have reduced the length and severity of the outbreak, but the number of unvaccinated people in the hardest hit age group remains a cause for concern.”
She added: “Vaccination sessions are continuing in schools throughout Wales and I urge pupils and their parents to take advantage of these.”
Source: Read More at BBC Health