Routine Immunization Coverage and Child Mortality Time-series Analysis of Trends, Disruption, and Recovery —Liberia, 1999-2024
Domaine:
healthcareType de record:
paper
Créateur:
Udh
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Background: Routine childhood immunization is central to child survival, yet its long‑term relationship with child mortality and health‑system shocks is under‑described in fragile settings such as Liberia. The country has rebuilt its health system after civil conflict and faced major disruptions from the 2014–2016 Ebola epidemic and the COVID‑19 pandemic.
Methods: An ecological time‑series analysis study was conducted using national annual data for Liberia from 1999 to 2024. Outcomes were under‑five, infant, and neonatal mortality rates. Exposures were DTP1, DTP3, MCV1, BCG, protection at birth against tetanus (PAB), DTP1–DTP3 dropout, and a mean core vaccine coverage indicator. The primary analytic sequence comprised descriptive trend analysis, annual ecological correlations, and time-adjusted linear regression of under-five mortality on DTP3 with heteroskedasticity- and autocorrelation-consistent standard errors. Sensitivity analyses included models with conflict fatalities, one-year lagged DTP3, first-difference models, and GLS autoregressive models. Interrupted time-series models for U5MR, DTP3, and dropout included level and slope terms for Ebola (from 2014) and COVID-19 (from 2020). Survey-year contextual indicators were summarized descriptively.
Findings: Under‑five mortality declined from 208.0 to 86.4 deaths per 1,000 (≈58.5%), while DTP3 coverage rose from 52% to 83%, MCV1 from 69% to 82%, and DTP1–DTP3 dropout fell from 32 to 8 points. Annual levels showed strong inverse associations between under‑five mortality and PAB, DTP3, and mean core coverage, and a strong positive association with dropout. Time‑adjusted annual models preserved these associations, including in a conflict‑adjusted specification, but GLSAR(1) and first‑difference models indicated that much of the signal reflected shared secular trends rather than short‑term effects. Ebola was associated with marked declines in DTP3 and worsening dropout, whereas mortality showed only modest short‑term changes amid a continued long‑run decline. Contextual indicators improved concurrently.
Interpretation: In Liberia, rising routine immunization coverage and declining child mortality have moved together over more than two decades, with shocks disrupting immunization more visibly than mortality. These ecological associations should not be interpreted as individual-level causal effects and appear to reflect long-run co-movement in immunization and broader child survival determinants. Resilient, integrated immunization systems and concurrent investments in other child survival interventions are needed to sustain gains in fragile and post-crisis settings.
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