Survey of immunity to measles in schoolchildren in Cork

Surveillance of measles in the Republic of Ireland has relied until now on notifications of clinically diagnosed infections and a manual system for monitoring coverage. In the light of a measles epidemic predicted in the United Kingdom in 1995, it was considered timely to review the epidemiology of measles and obtain baseline seroepidemiological data on measles immunity in Cork City in the Republic of Ireland. The age specific prevalence of measles IgG in saliva from 2000 schoolchildren aged 5 to 15 years was determined. The study also compared susceptibility rates in children with and without a history of measles vaccination or infection. Histories provided by parents were found to be unreliable in informing vaccination practice, as 79 of the 102 seronegative children would have been classified as immune. The proportion of children immune to measles, as gauged by seropositivity, was 91.9% in children aged 5 to 10 years and 95.8% in 11 to 15 year olds. The implications of the study results are discussed in relation to future prevention and control strategies.