Trends of inequality in DPT3 immunization services utilization in Ethiopia and its determinant factors: Evidence from Ethiopian demographic and health surveys, 2000–2019
Authors: Fekadu Hailu , Mekonnen Wubegzier , Adugna Aynalem , Kloos Helmut , Hailemariam Damen 
Published: January 2024

Background
Low levels of diphtheria, tetanus toxoid, pertussis (DPT3) immunization services utilization and high deaths among under five children are concentrated in economically and socially disadvantaged groups, especially in low and middle-income countries, including Ethiopia. Hence, the aim of this study is to assess levels and trends in DPT3 immunization services utilization in Ethiopia and identify inequalities.

Methods
This study used data from 2000, 2005, 2011, 2016, and 2019 Ethiopian Demographic Health Surveys (EDHSs). The 2019 updated version of the world health organization (WHO’s) Health Equity Assessment Toolkit (HEAT) software was used to analyze the data. Six measure of inequality was calculated: ratio (R), differences (D), relative index of inequality (RII), slope index of inequality (SII), population attributable fraction (PAF) and population attributable risk (PAR). The findings were disaggregated by the five equity stratifiers: economic status, education, place of residence, regions and sex of the child.

Results
This study showed an erratic distribution of DPT3 immunization services utilization in Ethiopia. The trends in national DPT3 immunization coverage increased from 21% in (2000) to 62% in (2019) (by 41 percentage points). Regarding economic inequality, DPT3 immunization coverages for the poorest quintiles over 20 years were 15.3% (2000), and 47.7% (2019), for the richest quintiles coverage were 43.1 (2000), and 83.4% (2019). However, the service utilization among the poorest groups were increased three fold compared to the richest groups. Regarding educational status, inequality (RII) show decreasing pattern from 7.2% (2000) to 1.5% in(2019). Concerning DPT3 immunization inequality related to sex, (PAR) show that, sex related inequality is zero in 2000, 2005 and in 2019. However, based on the subnational region level, significance difference (PAR) was found in all surveys: 59.7 (2000), 51.1 (2005), 52.2 (2011), 42.5 (2016) and 30.7 (2019). The interesting point of this finding was that, the value of absolute inequality measures (PAR) and (PAF), are shown a decreasing trends from 2000 to 2019, and the gap among the better of regions and poor regions becoming narrowed over the last 20 years. Concerning individual and community level factors, household wealth index, education of the mother, age of respondent, antenatal care, and place of delivery show statically significant with outcome variable. Keeping the other variables constant the odds of an average child in Amhara Region getting DPT3 immunization was 54% less than for a child who lived in Addis Ababa (OR: 0.46, 95% CI: 0.34 – 0.63). Respondents from households with the richest and richer wealth status had 1.21, and 1.26 times higher odds of DPT3 immunization services utilization compared to their counterpart (OR: 1.21, 95% CI: 1.04 -1.41) and (OR: 1.26, 95% CI: 1.13 – 1.40) respectively.

Conclusion
We conclude that DPT3 immunization coverage shows a growing trend over 20 years in Ethiopia. But inequalities in utilization of DPT3 immunization services among five equality stratifies studied persisted. Reasons for this could be complex and multifactorial and depending on economic, social, maternal education, place of residence, and healthcare context. Therefore, policy has to be structured and be implemented in a ways that address context specific barriers to achieving equality among population sub-groups and regions.