A Standardized Approach for Measuring Multi-Dimensional Equity in Vaccination Coverage, Cost-of-Illness, and Health Outcomes: Evidence from the Vaccine Economics Research for Sustainability & Equity (VERSE) Project

Background: Following a call from the World Health Organization in 2017 for a dashboard to monitor immunization coverage equity in line with the 2030 Agenda for Sustainable Development, this study proposes a new methodology and toolkit for measuring and tracking multi-dimensional equity in vaccine coverage, economic impact, and health outcomes.   Methods: The Vaccine Economics Research for Sustainability & Equity (VERSE) composite vaccination equity assessment metric is derived from literature on the measurement of socioeconomic equity combined with measures of direct unfairness in healthcare access. The metric takes the form of a concentration index of vaccination coverage, where instead of ranking individuals by income, individuals are ranked by multi-dimensional unfairness in access. The direct unfairness ranking variable is the predicted vaccination coverage from a logistic model based upon multiple dimensions of fair and unfair sources of variation in vaccination coverage. Fair sources of variation in coverage may include whether the child is underage to receive the vaccine according to the national immunization schedule. Unfair sources of variation may include sex of the child, maternal education, or socioeconomic status. Regression decomposition is applied to determine the relative share each unfair dimension has on overall inequality in vaccination status. These methods are applied to the most recent National Family Health Survey (NFHS) from 2015-2016 in India to assess the equity in fully immunized for age vaccination coverage and zero-dose status. Equity results are computed by state and nationally and compared with coverage to produce an equity-coverage plane.   Results: The multi-dimensional equity measure in is 0.105 (SE: 0.003) and 0.068 (SE: 0.005) for zero-dose status and fully immunized for age respectively. The most disadvantaged quintile is therefore 10.5% more likely to be zero-dose than the most advantaged quintile or 6.8% less likely to be fully immunized. The primary driver of unfair disadvantage in zero-dose status and fully immunized status, respectively, is maternal education accounting for 31.4% and 18.9% of observed inequality, followed by socioeconomic status contributing 15.9% and 14.9%, and health insurance coverage contributing 7.0% and 4.16%.   Conclusions: Our work builds upon existing methods and toolkits by providing a standardized method for measuring equity across multiple dimensions. It also allows policymakers to determine the relative magnitude of drivers of overall equity in vaccine outcomes rather than only the drivers of socioeconomic or unidimensional equity. Additionally, the toolkit expands the available outcomes for inequity analysis from coverage to include financing and health outcomes. This framework could be adapted to track equitable progress toward Universal Health Coverage (UHC) beyond the vaccine space. Funding: The Vaccine Economics Research for Sustainability & Equity (VERSE) project is funded by the Bill & Melinda Gates Foundation under award INV-003813 Declaration of Interest: None to declare. Ethical Approval: The Vaccine Economics Research for Sustainaability & Equity (VERSE) project, under which this study falls, obtained IRB approval from the Johns Hopkins Bloomberg School of Public Health IRB (IRB00014999).