Diminished returns of maternal education on children's vaccination status for indigenous women in Peru.

Objective: To assess the mediating and moderating roles of maternal education on ethnic disparities in children's vaccination status in Peru.

Methods: This was a cross-sectional study based on the secondary analysis of the 2023 Demographic and Health Survey. Children's vaccination status was defined as having completely received BCG; three doses of DPT and polio vaccines; and MMR vaccine by 12 months of age. Linear and Poisson regression models by ethnicity were fitted to assess the effect of maternal education on vaccination status. The 4-way decomposition using interventional analogues of natural effects was performed with the g-formula to assess the mediating and moderating roles of education on the disparity in vaccination status by mother's self-reported ethnicity (Indigenous versus Mestizos).

Results: A total of 5,622 Indigenous and 6,939 Mestizo children were included. The proportion of incomplete vaccination was 27.6% in Indigenous children and 21.6% in Mestizo children. Among Indigenous children, secondary and higher maternal education were associated with a 5 and 4 percentage point reduction in incomplete vaccination [-0.05 (95% CI: -0.08,-0.02) and -0.04 (95% CI: -0.07,-0.01), respectively]; while among Mestizo children, the reductions were 8 and 11 percentage points [-0.08 (95% CI: -0.11,-0.06) and -0.11 (95% CI: -0.13,-0.08)], compared to mothers who completed less than secondary education. Poisson models were consistent with the linear model. The mediation analysis showed large negative interaction, representing the reduced benefit of higher educational attainment for Indigenous women.

Conclusion: Smaller beneficial effects of maternal education level on children's vaccination status for Indigenous relative to Mestizos. Increasing education levels for all groups would inadvertently amplify existing ethnic gaps.