This project continues our collaboration with GAVI to locate and count children who are missing out on life-saving vaccines. By combining detailed population maps with local health data, the team identifies exactly where “zero-dose” or under-vaccinated children live. This work specifically focuses on vulnerable and marginalised groups, such as those in remote rural areas, crowded urban slums, and regions affected by conflict. 

Creating Better Population Maps 

The first goal is to update global population maps for the years 2015 to 2030 using the latest census information and geographic data. These maps provide a clearer picture of population trends by age and sex, with a special focus on children under the ages of one and five. For many countries, the team creates custom “bespoke” models that are more accurate for local needs than standard global estimates.  

Reaching the Hardest-to-Reach Areas 

WorldPop has developed specialised methods to find children in challenging environments, like informal settlements or conflict zones. As these methods have become standard, the team is handing over this routine work to the Institute for Health Metrics and Evaluation (IHME) to ensure these estimates are integrated into long-term global health planning. Meanwhile, WorldPop will continue exploring new data, such as those that help to identify informal settlements, internally displaced population and conflict affected areas, to better understand how displacement and violence affect a child’s chance of being vaccinated. 

Measuring Travel Time to Health Care 

Living far from a clinic is a major barrier to vaccination. This project uses travel-time data to estimate how many unvaccinated children live in remote areas. By measuring the time it takes to reach the nearest health facility, whether by walking or using a vehicle, the project identifies physical barriers to care. This information helps health officials see the proportion of children left behind due to distance, allowing for better planning of mobile clinics or new facility locations. 

Improving Local Vaccination Data 

Often, official health records at the district level can contain errors or missing information. Our team is developing smarter ways to fix these issues by combining routine health records, disease monitoring, and household surveys. Initially focusing on countries like Nigeria, Ethiopia, and Ghana, these new models provide a more accurate picture of which districts are meeting vaccination goals. The project also includes creating visualization tools to make this data easier for local decision-makers to interpret and use. 

Flexible Support for Changing Needs 

The project remains flexible to tackle new challenges as they arise, to ensure that Gavi always has the most relevant and up-to-date data to reach the world’s most vulnerable children. 

Link image: Ghana steps up drive to revamp routine immunization, WHO Ghana Country Office, 2023.