The World Health Organization had classified vaccine hesitancy as a threat to global health. A well-known phenomenon in high-income countries, we hypothesized that vaccine hesitancy might be emerging in low- and middle-income countries as well. Since immunization coverage usually shows social gradients with higher levels among wealthy than among poor individuals, we investigated whether the classical pro-rich pattern of immunization coverage changed over time in low- and middle-income countries. For that, we analyzed the current status of inequalities by wealth on immunization coverage and the trend of immunization coverage in both the poorest and wealthiest groups. We relied on nationally representative datasets from the Demographic and Health Surveys (DHS) and the Multiple Indicator Cluster Surveys (MICS) from 86 countries. We defined full immunization coverage (FIC) as the percentage of children aged 12-23 months who received dose each of BCG and MCV and 3 doses each of vaccines against DPT and polio. Eleven countries showed higher FIC in the poor in the most recent survey, accounting for 20% of upper middle−and 7% of low-income countries. Among those countries, 5 showed FIC declines over time in the wealthiest quintile, and 4 switched from pro-rich to pro-poor patterns throughout the years. In summary, this study found that the classical pro-rich inequality pattern, in which the wealthy present better coverage than the poor, appears to be changing, especially in upper-middle income countries. This shift is probably due to vaccine hesitancy among wealthy families.

This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health. A full version of the paper is available at doi.org/10.1016/j.amepre.2020.07.028.