Immunization Coverage in Low- and Middle-Income Countries

Immunization coverage in low- and middle-income countries (LMICs) represents a cornerstone of global health, yet it remains uneven and frequently below target levels. Routine vaccination programmes have expanded substantially over recent decades, driven by international alliances and domestic policy reforms. Despite these advances, substantial gaps persist both between and within countries. Barriers include limited access to health facilities, cold-chain disruptions, socio-economic inequalities and variable community engagement. Supplementary immunisation activities (SIAs) have been introduced in many settings to reach children missed by routine services, but their efficiency must be balanced against the need for sustainable, system-based delivery. Disruptions caused by pandemics, political instability and resource constraints have further threatened progress, highlighting the importance of resilient delivery platforms. Recent modelling studies have quantified the health impact of existing programmes, revealing large numbers of cases, deaths and disability-adjusted life-years averted, while economic evaluations underscore a favourable benefit-cost ratio. Innovative approaches to monitoring and evaluation, including household surveys, facility assessments and dynamic transmission models, are improving our understanding of coverage trends and informing adaptive strategies. Addressing the remaining shortfalls will require integrated action on supply-side strengthening, demand-generation through community engagement and data-driven decision making to ensure that all children in LMICs can realise the full protection offered by vaccines.

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Immunization Coverage in Low- and Middle-Income Countries publication trend

The graph below shows the total number of articles in immunization coverage in low- and middle-income countries across all publications each year (not limited to Nature Index journals).

Technical terms

Immunization coverage: The proportion of a target population that has received specified vaccine doses by a given age.

Supplementary immunisation activities (SIAs): Campaigns offering vaccination to broad age groups regardless of prior immunization status to rapidly boost immunity levels.

Disability-adjusted life-year (DALY): A composite measure of overall disease burden, expressed as the sum of years of life lost and years lived with disability.

Dynamic compartmental model: A mathematical simulation dividing a population into health states (e.g. susceptible, infected, recovered) to predict disease transmission and control interventions.

References

1. Health impact and economic evaluation of the Expanded Program on Immunization in China from 1974 to 2024: a modelling study. The Lancet Public Health (2025).
2. Health effects of routine measles vaccination and supplementary immunisation activities in 14 high-burden countries: a Dynamic Measles Immunization Calculation Engine (DynaMICE) modelling study. The Lancet Global Health (2023).
3. Estimating the health impact of vaccination against ten pathogens in 98 low-income and middle-income countries from 2000 to 2030: a modelling study. The Lancet (2021).