Measles cases outside a region battling a major epidemic are rising faster than at the epicentre for the first time.
The number of cases across Wales has outstripped the rise in the greater Swansea area, where a massive vaccination programme is still under way.
Health chiefs are warning the hardest hit 10 to 18 age group in Wales need vaccination protection as a “matter of urgency”.
Worrying numbers of the most at risk group remain unprotected and are failing to come forward to get the measles, mumps and rubella (MMR) vaccination, they said.
Public Health Wales (PHW) warned not enough children were being vaccinated to prevent further measles outbreaks.
An extra 22 measles cases have been reported in the greater Swansea area since last Thursday, taking the headline total to 1,061.
That number was eclipsed by the rest of Wales, which saw 32 extra measles case over the same period, taking the combined total to 1,224.
Figures released by PHW show a welcome drop in the rate of increase of the disease in the worst affected area.
But health chiefs were quick to point out that 22 cases in less than a week left no room for complacency.
As recently as 2011 there were 19 recorded cases of measles in Wales over the whole year.
While the rise in cases outside of the greater Swansea area is worrying, half of them, 16, are in the Gwent health board area, it was revealed.
It has already launched a large-scale vaccination programme targeting 10,000 unprotected 10 to 18-year-olds.
Outside of the greater Swansea area, efforts are being stepped up to prevent the spread of the disease by giving the MMR jab.
“PHW is reminding young people and their parents that the hardest hit group in the current outbreak is the 10 to 18 age group,” a spokesman said.
“Anyone of this age who has not yet received two doses of the MMR vaccine should be vaccinated as a matter of urgency.”
Dr Marion Lyons, PHW director of health protection, said: “I am delighted to see that more than 33,000 non-routine MMR vaccinations have been given since this outbreak started in November but it is concerning to us that only around 8,000 of these are aged 10 to 18, and this is the age group most affected.
“In each health board area we still have thousands of people in that age group needing to be vaccinated and we cannot emphasise enough how dangerous measles can be, how rapidly it can spread when unvaccinated children gather together and how easy it is to prevent by vaccination.
“Further outbreaks are a real possibility and will only be prevented if parents and young adults engage with the health services and take advantage of the many opportunities being offered for MMR vaccination.”
Vaccination sessions were continuing in schools across Wales, and further Saturday drop-in clinics will be held in the Abertawe Bro Morgannwg University Health Board area this weekend.
On Saturday, clinics will be held at Singleton and Morriston Hospitals in Swansea, the Princess of Wales Hospital in Bridgend, and Neath Port Talbot Hospital between 10am and 4pm. No appointment is needed.
Dr Lyons added: “Those not vaccinated are highly likely to catch measles, which is highly contagious.
“It is just a matter of time before a child is left with serious and permanent complications such as eye disorders, deafness or brain damage, or dies.
“The MMR vaccine is recommended by the World Health Organisation, UK Department of Health and Public Health Wales as the most effective and safe way to protect children against measles.”
Unvaccinated children aged between six and 12 months living in or travelling to the outbreak areas of Swansea and Neath Port Talbot or North Powys can be offered vaccination by their GP.
There is no adverse effect to this extra jab and those children would still need to receive the recommended two doses at 12 months and three years and four months of age.
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