The fully immunized child: Summarizing intracountry inequalities in coverage with seven routine vaccines in 195 countries and territories

Abstract

Introduction: Failures to achieve equal access to vaccines are inhibiting progress in boosting global vaccine coverage to meet Global Vaccine Action Plan (GVAP) and Sustainable Development Goal (SDG) targets. Past efforts to quantify the distribution of vaccines in terms of full immunization coverage have been limited in scope and comparability. In this study, we produce a complete time series of estimates of the proportion of surviving children fully immunized with seven routine childhood immunizations in 195 countries and territories. Methods: We synthesized 563 household surveys with individual-level information on vaccination status using spatiotemporal Gaussian process regression and probability theory to quantify full immunization coverage from 2006 (the first year of rotavirus vaccine introduction) to 2017. Results were constrained to antigen-specific vaccine coverage estimates from the Global Burden of Disease (GBD) project and routine introduction data from the WHO Joint Reporting Process. Results: In 2017, 93 countries and territories had introduced all seven key routine childhood immunizations—DTP3, MCV1, Polio3, HepB3, Hib3, PCV3, and RotaC. On a global scale and in all seven super regions, introducing more newly recommended vaccines contributed to massive gains in full immunization coverage. Latin America and the Caribbean stands out as a high achiever of full immunization coverage, with most countries including all seven vaccines in the schedule by 2017. Globally, 99 million one-year-olds remained underimmunized in 2017, representing a 21.8% decline from 2010. Discussion: Although introductions of new vaccines and investments in vaccination programs to scale-up coverage have contributed to global improvements in immunization coverage, more than two-thirds of one-year-olds are still missing at least one key childhood vaccine. Continuing to focus on the distribution of vaccines—as opposed to antigen-specific coverage—is important for assessing GVAP and SDG goals of boosting universal access.