Coverage, effectiveness, and sero-positivity of measles-containing vaccines in low- and lower middle-income countries: An umbrella review of systematic reviews and meta-analyses

BACKGROUND: Despite global investments, achieving measles elimination targets remain elusive in low- and middle-income countries (LMICs). This study provides a comprehensive synthesis of measles-containing vaccine (MCV) coverage trends, effectiveness, and uptake determinants to inform strategic realignment. METHODS: We conducted an umbrella review of systematic reviews (2010-2025) and analyzed World Health Organization/UNICEF coverage data (2000-2024) for 79 LMICs. Determinants were synthesized via meta-meta-analysis. RESULTS: Twelve reviews and longitudinal data for 79 countries were analyzed. In 2024, mean MCV1 coverage was 79.2% (SD = 16.0%), with only 17 countries (21.5%) achieving the ≥95% elimination threshold. MCV2 coverage averaged 69.4% (SD = 19.9%) and a mean dropout gap (difference between MCV1 and MCV2) of 10.9 percentage points. Regional disparities were profound: the regions of Americas and Africa recorded the lowest mean MCV1 coverage (74.3% and 76.8%, respectively), while the African Region faced critical gaps in MCV2 (64.9%). Meta-meta-analysis identified positive maternal perception (pooled odds ratio [OR] = 4.05; 95% confidence interval: 2.89-5.66) and awareness of benefits (pooled OR = 2.99) as the strongest predictors of uptake. CONCLUSION: Fewer than one-quarter of LMICs currently meet measles elimination targets. The stagnation in coverage and significant dropout rates necessitate a strategic shift to prevent measles resurgence and protect vulnerable children.