Pro-rich or pro-poor? socioeconomic inequities in under-immunization and access to childhood vaccination services in Nigeria

Abstract

Despite global progress, socioeconomic and geographic disparities continue to limit equitable access to childhood vaccination in low- and middle-income countries. Efforts to design equity-focused immunization strategies in Nigeria are constrained by limited empirical evidence on the distribution of access to childhood vaccination services across socioeconomic groups. This paper provides new decision-making relevant evidence on socioeconomic inequities in both under-immunization and access to childhood vaccination services in Nigeria. A cross-sectional household survey was conducted in six Nigerian states, each representing one of the six geopolitical zones. Data were collected from 1,734 caregivers of children under five using a questionnaire adapted from the WHO BeSD tool. Two key dimensions were assessed: vaccination status and ease of accessing childhood vaccination services. A wealth index derived from household assets and living conditions was used to categorise households into socio-economic status (SES) quintiles. SES inequities were assessed using the Erreygers-corrected concentration index for binary outcomes and bounded concentration indices for ordinal variables. Access to vaccination services varied by socioeconomic status. Among Among caregivers in the poorest wealth quintiles, 56.8% (95% CI: 51.5%–62.0%) reported “very easy” access, compared to 75.6% (95% CI: 70.8%–79.9%) in the richest quintile. Similarly, 49.6% (95% CI: 44.4%–54.9%) of caregivers in the poorest households rated vaccination costs as “very easy” to afford, compared with 68% (95% CI: 62.8%–72.9%) in the wealthiest group. Among all under-immunized children, 26.0% (95% CI: 20.7%–32.3%) were from the poorest wealth quintile, compared with 14.6% (95% CI: 11.0%–19.2%) from the richest quintile. Concentration indices (CI) confirmed significant pro-rich inequalities in overall ease of access (CI = 0.035, p  < 0.001) and affordability (CI = 0.034, p  < 0.001), while under-immunization was concentrated among the poor (CI = -0.048, p  = 0.005). Hence, poorer households experienced less favourable access and affordability and accounted for a larger share of under-immunized children, highlighting persistent socioeconomic inequalities in childhood vaccination. Childhood vaccination in Nigeria remains inequitable, varying significantly by SES, with poorer households facing greater barriers to access and higher under-immunization. Equity-focused services that harness potential in all sectors are needed to reduce inequities. Systematic monitoring of socioeconomic disparities and societal disruptions that reinforce under-immunization will ensure that adaptive strategies are mobilized early and no child is left behind. Not applicable.