Vaccine supply chains in resource-limited settings: Mitigating the impact of rainy season disruptions

The economic and man-made resources that sustain human wellbeing are not distributed evenly across the world, but are instead heavily concentrated in cities. Poor access to opportunities and services offered by urban centres (a function of distance, transport infrastructure, and the spatial distribution of cities) is a major barrier to improved livelihoods and overall development. Advancing accessibility worldwide underpins the equity agenda of 'leaving no one behind' established by the Sustainable Development Goals of the United Nations. This has renewed international efforts to accurately measure accessibility and generate a metric that can inform the design and implementation of development policies. The only previous attempt to reliably map accessibility worldwide, which was published nearly a decade ago, predated the baseline for the Sustainable Development Goals and excluded the recent expansion in infrastructure networks, particularly in lower-resource settings. In parallel, new data sources provided by Open Street Map and Google now capture transportation networks with unprecedented detail and precision. Here we develop and validate a map that quantifies travel time to cities for 2015 at a spatial resolution of approximately one by one kilometre by integrating ten global-scale surfaces that characterize factors affecting human movement rates and 13,840 high-density urban centres within an established geospatial-modelling framework. Our results highlight disparities in accessibility relative to wealth as 50.9% of individuals living in low-income settings (concentrated in sub-Saharan Africa) reside within an hour of a city compared to 90.7% of individuals in high-income settings. By further triangulating this map against socioeconomic datasets, we demonstrate how access to urban centres stratifies the economic, educational, and health status of humanity.

Abstract Objective To investigate disparities in full immunization coverage across and within 86 low- and middle-income countries. Methods In May 2015, using data from the most recent Demographic and Health Surveys and Multiple Indicator Cluster Surveys, we investigated inequalities in full immunization coverage – i.e. one dose of bacille Calmette-Guérin vaccine, one dose of measles vaccine, three doses of vaccine against diphtheria, pertussis and tetanus and three doses of polio vaccine – in 86 low- or middle-income countries. We then investigated temporal trends in the level and inequality of such coverage in eight of the countries. Findings In each of the World Health Organization’s regions, it appeared that about 56–69% of eligible children in the low- and middle-income countries had received full immunization. However, within each region, the mean recorded level of such coverage varied greatly. In the African Region, for example, it varied from 11.4% in Chad to 90.3% in Rwanda. We detected pro-rich inequality in such coverage in 45 of the 83 countries for which the relevant data were available and pro-urban inequality in 35 of the 86 study countries. Among the countries in which we investigated coverage trends, Madagascar and Mozambique appeared to have made the greatest progress in improving levels of full immunization coverage over the last two decades, particularly among the poorest quintiles of their populations. Conclusion Most low- and middle-income countries are affected by pro-rich and pro-urban inequalities in full immunization coverage that are not apparent when only national mean values of such coverage are reported.