High resolution global mapping of women of childbearing age, pregnancies and births for Zika burden estimation. (360G-Wellcome-204613_Z_16_Z)

Evidence is mounting on the link between Zika virus infections and birth defects, making an understanding oflikely numbers of pregnancies and births affected a high priority. Assessing the likely demands on healthservices, needs for future vaccines and estimating the current and future burden of the virus requiresaccurate estimates of the numbers at risk. It is clear that Zika transmission risk is spatially heterogenous, andmodelling efforts have recently mapped areas of suitability at high spatial resolution (Messina et al, Perkinset al, Samy et al), and will continue to be refined as more data become available. However, many of theareas predicted as suitable are unpopulated, while others are densely populated. Moreover, the numbers ofbirths and pregnancies can vary substantially within and between countries with significant spatial andtemporal variations in age-specific fertility rates evident (Tatem et al). Therefore, to transform theseecological niche, risk and transmission potential models into accurate estimates of burden that are neededto guide strategies and assess system demands, data on women of childbearing age, births and pregnanciesat similar levels of spatial disaggregation are required. The lack of such data has meant that existing studieshave been restricted to using simple national-level estimates to adjust gridded population datasets (Messinaet al, Perkins et al, www.worldpop.org.uk/zika/), ignoring spatial heterogeneities and likely leading toestimates that include substantial spatial biases.