Socioeconomic inequalities and measles immunization coverage in Ecuador: A spatial analysis.

Introduction/background: Inequalities in measles immunization coverage facilitate the onset of outbreaks. This study aimed to quantify socioeconomic inequalities associated with measles immunization coverage at the population level.

Methods: An ecological study was performed using two datasets: the results of a measles immunization survey performed in Ecuador, in 2011, and socioeconomic data from the 2010 census, aggregated by canton. The survey included 3,140,799 people aged 6 months to 14 years living in 220 cantons of Ecuador. Vaccinated children were considered those who received at least one dose of vaccine against measles. Multiple spatial regression was performed to identify socioeconomic inequalities associated with measles immunization coverage. The slope index of inequality and the relative index of inequality were calculated.

Results: Vaccination coverage against measles was inversely associated with unsatisfied basic needs in urban areas (P < 0.01) and the proportions of indigenous and African-Ecuadorian residents in the canton (P = 0.015), and directly associated with unemployment rate in the canton (P = 0.037). The distribution of immunization coverage across the cantons was heterogeneous, indicating spatial dependence. The non-immunization rate was 71% higher in the poorer cantons than in the upper stratum cantons (prevalence ratio 1.71; 95%CI: 1.69-1.72). A difference of 10.6 percentage points was detected in immunization coverage between cantons with the best vs. worst socioeconomic level, according to the slope index of inequality. The relative index of inequality revealed that immunization coverage was 1.12 times higher in cantons with the highest socioeconomic level vs. cantons with the lowest socioeconomic level.

Conclusions: The spatial dependence between measles vaccination coverage and socioeconomic disparities suggests clusters of vulnerable populations for outbreaks. Health and social inequalities must be considered to achieve and maintain measles elimination.