WHO and UNICEF estimates of national infant immunization coverage: methods and processes

Area of Science:

• Global Health
• Vaccinology
• Public Health Policy

Background:

• Routine immunization is critical for child survival and disease prevention.
• Accurate immunization coverage data is essential for monitoring global health progress.
• The World Health Organization (WHO) and United Nations Children's Fund (UNICEF) play a key role in global health data collection and analysis.

Purpose of the Study:

• To outline the methodology used by WHO and UNICEF for estimating national immunization coverage.
• To detail the vaccines included in the annual review and the data sources utilized.
• To emphasize the independent technical assessment provided by WHO and UNICEF regarding national immunization systems.

Main Methods:

• Annual review of government reports and supplementary survey data.
• Consultation with local experts, including national immunization system managers and WHO/UNICEF staff.
• Country-by-country data review using heuristics; no statistical models are employed.
• Draft estimates are shared with national authorities for review and feedback before finalization.

Main Results:

• WHO and UNICEF produce annual estimates of national immunization coverage for key vaccines.
• These estimates are based on a comprehensive review of reported data, literature, and expert input.
• The process ensures an independent technical assessment of national immunization system performance.

Conclusions:

• The WHO/UNICEF immunization coverage estimates provide a reliable measure of national immunization system performance.
• These estimates, available since 1980 and updated annually, are crucial for global health monitoring.
• The methodology ensures transparency and incorporates national feedback while maintaining independent assessment.