Lessons and challenges for measles control from unexpected large outbreak, Malawi

Andrea Minetti1, Matthew Kagoli, Agnes Katsulukuta

  • 1Epicentre, Paris, France. andrea.minetti@epicentre.msf.org

Insights

A 2010 measles outbreak in Malawi affected all age groups, despite high vaccination coverage. This highlights the need for improved outbreak preparedness and timely, targeted vaccination campaigns to prevent future measles epidemics.

Area of Science:

  • Epidemiology
  • Public Health
  • Vaccinology

Background:

  • Despite high reported immunization coverage in Malawi, a substantial measles outbreak occurred in 2010.
  • The outbreak resulted in 134,000 cases and 304 deaths, affecting all age groups, with significant impact on adults.

Purpose of the Study:

  • To investigate the factors contributing to the 2010 measles outbreak in Malawi.
  • To evaluate vaccine effectiveness and routine immunization coverage in relation to the outbreak.

Main Methods:

  • Analysis of outbreak data, including case numbers, deaths, and attack rates across different age groups.
  • Survey data on routine immunization coverage and supplementary immunization activities.
  • Calculation of vaccine effectiveness for one and two doses.

Main Results:

  • Highest attack rates were observed in young children, but individuals over 15 years old constituted 28% of all cases.
  • Routine immunization coverage varied significantly by age group, with lower coverage in younger children (9-11 months).
  • Vaccine effectiveness was 83.9% for one dose and 90.5% for two doses.

Conclusions:

  • A continuous accumulation of susceptible individuals over a decade likely fueled the measles outbreak.
  • Malawi, aiming for measles elimination, must enhance its outbreak preparedness strategies.
  • The timeliness and target population selection are critical for the success of reactive vaccination campaigns.

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