Population Estimates

Geospatial techniques can be used to map distribution of target populations for vaccination programs and other health interventions within the health cluster. These techniques can also be used to identify marginalized populations characterized by poor accessibility to health interventions. The most reliable population estimates used in geospatial data disaggregation is an up-to-date census of the country or health cluster. In situations where up-to-date census data is not available, alternative sources of obtaining population estimates can be explored. In an unpublished report from MSF,11 population estimation methodologies can be divided into three broad strategies, depending on the context within which these estimates are being conducted. When datasets are available (from the field), methods that can be used include geospatial interpolation, vaccination coverage, multiplier methods and the use of building footprints (plus estimates of household size). When in the field, the Quadrat, Transect, T-square and Delphi methods can be used. For remote work, the use of building footprints plus household sizes, and geospatial covariates (e.g land cover/use, night-time lights intensity) are among recommended methods.

WorldPop is an open spatial demographic data and research initiative that provides open access to archived spatial demographic datasets to support development, disaster response and health applications. These datasets cover Central and South America, Africa, and Asia. Global population estimates for 2020 for instance are made available through integrating census, microdata and survey estimates in a spatiotemporal modelling framework. 12 Another alternative source of obtaining valid population estimates is by conducting a micro-census informed by demarcated health or administrative boundary data. In the DRC for instance, the granularity in health boundary databases created by the OSM community allowed for community health workers to provide up-to-date population estimates through a micro-census, to guide programme implementation.