Resurgence of measles in Singapore: Profile of hospital cases

Objective: To ascertain the profile of cases of measles seen at a general h ospital during a recent outbreak that occurred despite a measles vaccinatio n program. Methodology: A retrospective study from January 1991 to March 1998. All pat ients with measles (ICD code 055.9) seen at the emergency unit or as inpati ents were included. Results: There were 87 cases identified. The diagnosis was clinical in all and proven serologically in 71%. Eighty-five per cent of the cases occurred between January 1997 and March 1998. There was a bi-modal age distribution with peaks in the very young (less than or equal to 18 months) and those a ged 16-20 years. The majority was unvaccinated (58/87). A proportion (11/87 ) demonstrated vaccine failure, most likely primary failures. Conclusions: This changing measles epidemiology suggests lowering of herd i mmunity. 'Catch up' vaccinations in July-October 1997 given to school child ren aged 12-18 years (200 000 individuals or 82% of cohort), may have helpe d contain the outbreak. These results substantiated the need for a two-dose policy and 'catch-up' immunization program.