State of Inequality in Childhood Immunization: Monitoring Progress Across Low- and Middle-Income Countries over the...

Background/Objectives: Sizeable between- and within-country inequalities in childhood immunization impair progress towards the goals set by the global Immunization Agenda 2030 (IA2030) of achieving universal coverage of all persons with essential life-saving vaccines. Monitoring global trends in immunization inequalities helps to identify population subgroups that are less likely to benefit from vaccines and provides evidence for tracking progress on regional and global goals and informing equity-oriented interventions. This paper assesses the state of within-country inequality in childhood immunization across low- and middle-income study countries. Methods: Using data from household health surveys, the analysis quantifies within-country inequality across up to 92 countries, areas and territories, for nine childhood immunization indicators (seven coverage indicators and two indicators of non-receipt of vaccines) by five dimensions of inequality (child sex, mother's age, mother's education, household economic status and place of residence). Absolute and relative summary measures of inequality (difference, ratio, slope index of inequality, relative index of inequality and population attributable risk) were calculated to assess the latest situation of inequality (i.e., using the most recent survey from 2014 to 2023) and change over time (i.e., comparisons with data from 2004 to 2013). Results: The latest situation of inequality revealed overall low or no inequality by child sex, mother's age and place of residence, with more pronounced inequality related to mother's education and household economic status. The median differences between the most and least educated subgroups ranged between 9 and 14 percentage points for immunization coverage indicators, and between 6 and 9 percentage points for non-receipt of vaccines indicators. The extent of inequality in childhood immunization tended to remain about the same as the previous decade, with modest reductions in absolute economic-related and place of residence inequality in DTP3 immunization, as well as place of residence inequality in full immunization (declining by 3.25, 2.42, and 2.16 percentage points over 10 years, respectively). Distinct patterns of economic-related inequality were evident across country income groups, with low-income countries reporting larger inequality than lower- and upper-middle-income countries; there was substantial variation at the country level. Conclusions: Economic- and education-related inequalities in childhood immunization within low- and middle-income countries have persisted over the past decade.