Sociodemographic Inequalities in COVID-19 Booster Dose Vaccination Coverage: a Retrospective Study of 196 Provinces in Peru.

Background: The COVID-19 vaccination coverage shows variability in booster doses between residency areas or ethnicity. The aim of this study was to evaluate how sociodemographic conditions influence unequal vaccination coverage with booster doses against COVID-19 in Peru.

Methods: A retrospective, ecological study with an evaluation of 196 provinces in Peru. The sociodemographic conditions were evaluated as sources of inequality (sex, age group, educational level, residence area, and ethnic group). The inequality measure used was the GINI, an index that show the inequal vaccination coverage with third and fourth booster doses against COVID-19 in Peruvians provinces. The index allow determinate a higher inequality when the value is near to 1, and a lower inequality when the value is near to 0. Also, the impact of each sociodemographic condition in the general inequality was evaluate with a decomposition analysis of GINI coefficient into Sk (composition effect), Gk (redistribution effect), Rk (differential effect).

Results: In provinces evaluated the mean vaccine coverage for the third and fourth booster doses was 57.00% and 22.19%, respectively at twelve months since the beginning of vaccination campaign. The GINI coefficient was 0.33 and 0.31, for the third and fourth booster doses coverage, respectively. In the decomposition analysis, twelve months after the start of the third and fourth dose vaccination campaign, revealed higher Sk values for people living in rural areas (Sk = 0.94 vs. Sk = 2.39, respectively for third and fourth dose), while higher Gk values for Aymara (Gk = 0.92 vs. Gk = 0.92, respectively), Quechua (Gk = 0.53 vs. Gk = 0.53, respectively), and Afro-Peruvians (Gk = 0.61 vs. Gk = 0.61, respectively). Also, higher negative correlation in Rk values for people with elementary education (Rk=-0.43 vs. Rk=-0.33, respectively), aged between 15 and 19 years (Rk=-0.49 vs. Rk=-0.37, respectively), and Aymara (Rk=-0.51 vs. Rk=-0.66, respectively).

Conclusion: The rural residency area, lower education and Quechua, Aymara or Afro-Peruvians ethnicity determinated inequalities in vaccination coverage with booster doses against COVID-19 in Peruvian provinces.