title: Measuring populations to improve vaccination coverage.
abstract: In low-income settings, vaccination campaigns supplement routine immunization but often fail to achieve coverage goals due to uncertainty about target population size and distribution. Accurate, updated estimates of target populations are rare but critical; short-term fluctuations can greatly impact population size and susceptibility. We use satellite imagery to quantify population fluctuations and the coverage achieved by a measles outbreak response vaccination campaign in urban Niger and compare campaign estimates to measurements from a post-campaign survey. Vaccine coverage was overestimated because the campaign underestimated resident numbers and seasonal migration further increased the target population. We combine satellite-derived measurements of fluctuations in population distribution with high-resolution measles case reports to develop a dynamic model that illustrates the potential improvement in vaccination campaign coverage if planners account for predictable population fluctuations. Satellite imagery can improve retrospective estimates of vaccination campaign impact and future campaign planning by synchronizing interventions with predictable population fluxes.
authors.affiliation: Biology Department; Center for Infectious Disease Dynamics, Pennsylvania State University, University Park PA, USA.|Woods Institute for the Environment, Stanford University, Stanford CA, USA.
authors.forename: Nita
authors.initials: N
authors.lastname: Bharti
authors.affiliation: Université de Niamey, Niamey, Niger.
authors.forename: Ali
authors.initials: A
authors.lastname: Djibo
authors.affiliation: Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.|WorldPop, Department of Geography, University of Southampton, Southampton, UK.|Flowminder Foundation, Stockholm, Sweden.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tatem
authors.affiliation: Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.|Department of Ecology and Evolutionary Biology; Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton NJ, USA.
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Grenfell
authors.affiliation: Biology Department; Center for Infectious Disease Dynamics, Pennsylvania State University, University Park PA, USA.|Department of Statistics, Pennsylvania State University, University Park PA, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ferrari
mesh_terms: D004196:Disease Outbreaks / Q000517:prevention & control / Q000706:statistics & numerical data*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D032541:Mass Vaccination / Q000706:statistics & numerical data*; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control; D009548:Niger / Q000453:epidemiology; D011156:Population Density; D011157:Population Dynamics; D012189:Retrospective Studies; D063809:Satellite Imagery / Q000379:methods*; D012959:Socioeconomic Factors