Catching measles in an appropriately vaccinated group: a well-circumscribed outbreak in the South East of Ireland,...

A measles outbreak occurred in a school in a small town in the South East of Ireland in September-November 2013. Most (and all early) cases had one dose of the measles-mumps- rubella (MMR) vaccination. All suspected cases were followed up, in order to advise on sampling and provide public health advice to them and their contacts. MMR vaccination control measures were instituted in the town. These included early second MMR in primary schools and childcare facilities, bringing forward the planned school MMR catch-up programme, early first MMR dose for children aged 6-12 months and targeted advice to unvaccinated children. There were 20 cases (17 confirmed) of measles associated with the outbreak. Fifteen cases occurred in the index school, with four in pre-school-age children (<4 years) who had clear epidemiological links with children at the school. This was a well-circumscribed outbreak occurring, unusually, in a well-vaccinated population. The outbreak came late to the attention of Department of Public Health staff but prompt action, once notified, and institution of control measures resulted in quick termination of the outbreak and prevention of cases in a neighbouring city.