The number of measles cases recorded in the Swansea outbreak has passed 1,000, according to Public Health Wales.
An ITV News/Com Res poll has found 71% of people think parents are acting irresponsibly if they don't get the MMR jab for their children.
71% of people think parents who do not vaccinate their children with MMR vaccine are being irresponsible, a ITV News/Com Res poll suggests.
More than 200 at-risk school children are to be given the MMR jab after a measles case was confirmed in a region recovering from a major epidemic.
Pupils at a south Wales school will be given the triple vaccine as concerned health chiefs act to avert a new outbreak of the potential killer illness.
A massive programme to inoculate thousands of children was launched in the greater Swansea area in the spring as it battled a major measles outbreak. Large numbers of previously unprotected children were given the triple measles, mumps and rubella (MMR) jab as a result.
The new case comes three months after the end of that epidemic - the biggest outbreak of measles ever to hit Wales. More than 1,200 people contracted measles, 88 serious enough to visit hospital, and one person died in the outbreak which began in November last year.
The number of confirmed measles cases in England fell to 113 in June, Public Health England announced.
This was down from 193 cases in May and "follows the nationwide rollout of the MMR catch-up programme", the organisation said.
Head of immunisation Dr Mary Ramsay said it was "still too early to be confident" that the drop in measles cases was a result of the campaign, "but we are making good progress towards the 95% target".
A measles epidemic that swept across south Wales is beginning to slow down, health experts have said. However they warn that not enough young people are immunised against the disease.
According to Public Health Wales (PHW), six new cases have been reported since Tuesday.
This brings the total number of those who have contracted measles in the past six months to 1,158. That compares with 19 cases for the whole of 2011.
PHW officials said almost 2,500 non-routine MMR jabs have been given out within the past week.
Read more on ITV Wales.
Public Health Wales is warning of its concerns that outbreaks of measles may start to be seen outside of the Swansea area as cases continue to be reported across Wales.
There have now been 1,074 cases of measles in the area affected by the outbreak – an increase of 13 in the last two days – and 1,237 across the whole of Wales.
Dr Marion Lyons, Director of Health Protection for Public Health Wales, said: “Thirteen new cases in the last two days may not seem like a lot, but it should be remembered that in 2011, we only saw 19 measles cases in the whole of Wales for the whole of the year.
“There is no way of knowing where the next outbreak could strike so the message is simple – wherever you live in Wales, if you are a young person who hasn’t received two doses of MMR or the parent of a child who hasn’t, please arrange vaccination urgently".
The efforts to vaccinate susceptible children in the Abertawe Bro Morgannwg University Health Board area have been tremendous and we are delighted to see that around half of children needing vaccination have now received the MMR.
But with around 50,000 children in the 10 to 18 age group still not vaccinated, and more than 1,000 cases now reported to us, we cannot be complacent.
– Dr Marion Lyons, Director of Health Protection for Public Health Wales
While not enough children are vaccinated, this outbreak can easily spread anywhere in Wales.
Therefore we urge parents of children, and young people themselves, to take up opportunities to receive the MMR vaccine as a matter of urgency.
The number of measles cases recorded in the Swansea outbreak - which started last November - has passed 1,000, Public Health Wales said.
Some 1,011 cases have now been recorded and 9,000 people aged between 10 and 18 still need to be vaccinated.
In the last month, 4,000 people have received the MMR jab.
But Public Health Wales has warned that the country as a whole needs to replicate Swansea's response to the outbreak, with 50,000 10 to 18 year-olds still unvaccinated across Wales.
Children at private schools face the greatest risk from the measles outbreak and could pose a health threat to the rest of the population, a leading doctor has warned.
Professor John Ashton said Britain's 600,000 privately-educated children were at much greater risk of infection than those in the state sector.
Prof Ashton said a mix of large numbers of middle-class children who were not vaccinated against measles following the Wakefield scare in the 1990s, along with pupils from overseas with unknown health records, meant schools could become "reservoirs of disease", the Daily Telegraph said.
He said the risk was similar to that from groups such as gypsies and travellers, who have previously spread the disease.
Prof Ashton, who will soon become president of the Faculty of Public Health, said: "You've got a lot of middle-class, well-off parents, large numbers of whom did not have their children immunised because of the Wakefield scare - which was a very middle-class phenomenon.
"Layered on top of that you have got a lot of children from abroad, especially from the Far East, from countries such as Hong Kong and China, and there are few checks being done to establish their immunisation records."