Peer-reviewed article
Data quality of reported child immunization coverage in 194 countries between 2000 and 2019
Cornelius Rau, Daniel Lüdecke, Laure B. Dumolard, Jan Grevendonk, Brenton M. Wiernik et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study assessed the quality of child immunization coverage data reported by 194 countries to WHO and UNICEF from 2000 to 2019, examining four vaccines: BCG, DTP, and measles. Overall, 18.2% of reported data had quality issues, but the probability of data quality problems declined by 5.1% per year globally. Regional variation was significant, with South-East Asia showing the best data quality (6.3% with issues) and the Americas showing the poorest (29.7% with issues). The findings indicate that global immunization data quality has improved over 20 years, though progress varies by region.
Key points
- 18.2% of globally reported immunization coverage data had quality flags indicating potential problems
- Data quality improved significantly over time, with a 5.1% annual decline in quality issues worldwide
- Africa showed the steepest improvement in data quality (-9.6% per year), followed by Europe (-5.4%) and the Americas (-4.9%)
- South-East Asia had the lowest probability of data quality issues at 6.3%, while the Americas had the highest at 29.7%
- No country group showed a statistically significant increase in data quality problems over the 20-year period
Limitations
This study measures data quality of reported coverage only and does not assess the actual accuracy of immunization coverage on the ground. It cannot distinguish between genuine programmatic improvement and improvements in data collection and reporting systems.
Abstract
Analyzing immunization coverage data is crucial to guide decision-making in national immunization programs and monitor global initiatives such as the Immunization Agenda 2030. We aimed to assess the quality of reported child immunization coverage data for 194 countries over 20 years. We analyzed child immunization coverage as reported to the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) between 2000-2019 by all WHO Member States for Bacillus Calmette-Guérin (BCG) vaccine birth dose, first and third doses of diphtheria-tetanus-pertussis-containing vaccine (DTP1, DTP3), and first dose of measles-containing vaccine (MCV1). We assessed completeness, consistency, integrity, and congruence and assigned data quality flags in case anomalies were detected. Generalized linear mixed-effects models were used to estimate the probability of flags worldwide and for different country groups over time. The probability of data quality flags was 18.2% globally (95% confidence interval [CI] 14.8-22.3). The lowest probability was seen in South-East Asia (6.3%, 3.3-11.8, p = 0.002), the highest in the Americas (29.7%, 22.7-37.9, p < 0.001). The probability of data quality flags declined by 5.1% per year globally (3.2-7.0, p < 0.001). The steepest decline was seen in Africa (-9.6%, -13.0 to -5.8, p < 0.001), followed by Europe (-5.4%, -9.2 to -1.6, p = 0.0055), and the Americas (-4.9%, -9.2 to -0.6, p = 0.026). Most country groups showed a statistically significant decline, and none had a statistically significant increase. Over the past two decades, the quality of global immunization coverage data appears to have improved. However, progress has not been universal. The results highlight the need for joint efforts so that all countries collect, report, and use high-quality data for action in immunization.