Measuring populations to improve vaccination coverage

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.