A measles epidemic controlled by immunisation

Area of Science:

• Epidemiology
• Public Health
• Immunisation Science

Background:

• A measles epidemic was predicted in 1997, necessitating a planned immunisation campaign.
• The measles-mumps-rubella (MMR) vaccine campaign was targeted at children aged 2-10 years.
• The epidemic commenced prior to the planned vaccination drive.

Purpose of the Study:

• To describe the 1997 measles epidemic and its characteristics.
• To evaluate the impact of the MMR vaccination campaign on measles incidence.
• To assess the effectiveness of the targeted immunisation strategy.

Main Methods:

• Data integration from measles hospitalisation, notification, and laboratory records.
• Analysis of epidemic timeline, case numbers, hospitalisations, and mortality.
• Calculation of age-standardised incidence and hospitalisation rates across different ethnic groups.

Main Results:

• The epidemic spanned April 1997 to January 1998, with 2,169 identified measles cases.
• Measles incidence and hospitalisation rates were significantly higher among Pacific people and Maori compared to Europeans.
• Incidence was highest in infants under one year, with children aged 10 and under driving transmission.

Conclusions:

• The MMR vaccination campaign averted 90-95% of predicted measles cases.
• The campaign's targeting of children aged 10 and under was appropriate and effective.
• The study highlights the importance of timely and well-targeted immunisation programs in controlling infectious disease outbreaks.