A measles epidemic controlled by immunisation

Aim. In 1997, an immunisation campaign, using measles-mumps-rubella vaccine , was planned for children aged 2-10 years to prevent a measles epidemic pr edicted by mathematical modelling. The epidemic started before the campaign and is described here. Method. Measles hospitalisation, notification and laboratory data were comb ined. Results. The epidemic started in April 1997 and was largely over by January 1998. No deaths were identified and only one hospitalisation was coded as measles encephalitis, compared to seven deaths and ten cases of measles enc ephalitis in the 1991 epidemic. For the 12 months from 1 March 1997 there w ere 2 169 (60 per 100 000) measles cases identified, 314 (9 per 100 000)df whom were hospitalised. Two-thirds of hospitalised cases were notified. The age-standardised measles incidence rates were 33, 34, and 174 per 100 0 00 for Europeans, Maori and Pacific people, respectively. The respective ag e-standardised hospitalisation rales were 4, 9 and 32 per 100 000. Measles incidence was highest for under one-year-olds (904 per 100 000) ana low for 11-16 year-olds (27 per 100 000) - the cohort previously offered a second vaccine dose. Most cases were aged 10 years and under, and this group were the main drivers of virus transmission. Conclusions, The immunisation campaign prevented 90-95% of predicted cases. The campaign was appropriately targeted at children aged 10 years and unde r.