Cases of measles in an outbreak centred on the Neath and Swansea area have now reached 36, according to Public Health Wales.
All of the cases in the outbreak – which has affected four schools in the Abertawe Bro Morgannwg University Health Board area – have been reported since the beginning of October.
Public Health Wales said the outbreak has the potential to keep spreading for as long as large numbers of people remain unvaccinated with MMR.
It added that several of the measles cases have been contracted within school from pupils who were sent to school with symptoms, when they should be kept at home.
Dr Jorg Hoffmann, consultant in communicable disease control for Public Health Wales, said: “One child with measles sitting in a classroom for just one hour will lead to at least 70% of other pupils who are not vaccinated catching measles.”
Public Health Wales said it was working closely with Abertawe Bro Morgannwg University Health Board to bring the outbreak under control and that vaccination sessions will be arranged at schools where there have been measles cases.
The outbreak comes less than four months after the end of Wales’s biggest measles outbreak since the introduction of MMR, which was centred on the same area and resulted in more than 1,200 cases of measles, 88 hospital admissions and one death.
Although more than 70,000 catch up doses of MMR were given across Wales during the outbreak, around 30,000 children and young people in the 10-18 age group remain unprotected.
Dr Hoffmann added: “We are very frustrated to see more cases of measles in the area so soon after the large outbreak earlier this year and we are very keen for this to be stopped before it can get any bigger.”
Public Health Wales is reminding those who received a first MMR dose as part of the vaccination drive held at the height of the outbreak earlier this year that two doses are needed for the maximum 99% protection.
In addition, adults who work in close contact with children, but who have never had measles or the MMR vaccine, are “urged” to ensure they speak to their GP about vaccination.
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