ALMOST 80pc of new measles case this year have been recorded in Dublin.
The worrying rise has prompted the HSE to contact doctors in the city "en masse" about the concerns.
It also plans to set up special MMR vaccination clinics in primary schools when schools re-open in September.
Some 110 measles cases have been detected in Ireland so far this year, at least eight of which were due to infection while travelling in Europe. In 87 of the cases, the children were living in the HSE East region, in or near Dublin and in almost half of cases, the children were eligible for vaccination but had not received any doses.
In 14 cases, the children were under a year old and too young to have been vaccinated. Only 90pc of Irish children over two years old have received the vaccine, which is below the target of 95pc to prevent measles outbreaks.
The measles vaccine is included in the MMR, which also immunises against mumps and rubella. It is usually administered at 12 months old and again at four to five years old and is free of charge from GPs.
Dr Mel Bates, medical director the out-of-hours doctor service DDoc said there was an "upsurge last weekend", with three or four children diagnosed with the disease.
"We are on heightened alert," he said, adding that the main issue was to ensure children had two doses of the MMR, one at 12 months old and one and at four or five years.
Dr Brenda Corcoran, head of the HSE National Immunisation Office, urged parents to immunise their children, particularly before travelling to Europe where there is an outbreak of the disease.
Over 21,000 cases have been reported in Europe since the beginning of the year, with more than half the cases reported in France. Six children have died in France, 14 suffered neurological complications and 444 suffered severe pneumonia.
Referring to the scare created by the now discredited Wakefield study drawing a link between MMR and autism, Dr Bates said he rarely encountered parents who are still concerned.
Immunisation rates fell dramatically to 75pc as a result of the Wakefield report.
Dr Bates warned that, because measles is a viral infection, there is no treatment for it and reminded parents that there was a risk to unvaccinated children.