More than 3100 children between the ages of 5 and 16 in the Cwm Taf University Health Board area have not received two doses of MMR vaccine and are at risk from measles, according to Public Health Wales.
The warning comes as a measles outbreak affecting the Newport and Torfaen areas continues, with 17 confirmed cases of the infection.
The outbreak can be directly linked to an ongoing outbreak of measles in Europe, which has seen more than 14,000 cases and dozens of deaths since the beginning of the year.
Although there are no confirmed measles cases in Cwm Taf University Health Board at present, Public Health Wales is warning that while the 95% vaccination target has not been reached, cases and outbreaks of this potentially deadly infection could be seen anywhere in Wales.
Kelechi Nnoaham, Director of Public Health for Cwm Taf University Health Board, said: “The simple, safe and effective way to stop measles is to have two MMR jabs.
“Parents appear to understand this well – the current outbreak in the Newport and Torfaen areas has resulted in more than 1,000 children receiving MMR vaccinations.
“With a large measles outbreak only a plane ride away in Europe, a new school term starting and popular events taking place throughout the season, there is a significant risk of unvaccinated children anywhere in Wales coming into contact with people who have measles, either at home or abroad.
“Children who have not received two doses of MMR are highly likely to contract measles if they come into contact with someone who has the infection, as it is very contagious.
“People who contract measles can be left with permanent disabilities, and the infection can even be fatal, and so I would urge parents of unvaccinated children not to be complacent.”
The symptoms of measles include a high temperature, cough, runny nose, red eyes (conjunctivitis), and a distinctive red rash.
Parents who suspect their child has measles should contact their GP or NHS Direct Wales on 0845 46 47 for an assessment. They should alert their health care providers of the symptoms before attending any appointment.
Parents whose children are not up to date with two doses of MMR should ensure that they contact their GP practice to arrange this quick, safe and effective vaccine.
Adults born since 1970, who have never had measles or the MMR vaccine, are also urged to ensure they contact their surgery about vaccination, especially if they work with children.
The first dose of MMR is usually given to babies at between 12 and 13 months of age, and the second at three years and four months of age, but it is never too late to catch up on missed doses.
About 1 in 5 children with measles can experience serious complications such as ear infections, pneumonia or meningitis. One in 10 children with measles ends up in hospital and in rare cases it can be fatal.
Further information on measles, including a link to a video testimony from a mother whose three year old unvaccinated daughter contracted measles, is available at http://www.publichealthwales.org/measles