How geospatial technology can help to zero in on zero-dose children

Combining geographical information on populations, locations of health care sites, and the movement of vaccinators can offer insights into how efficient and equitable vaccination coverage is, and has great potential to improve immunisation delivery.

  • 29 October 2020
  • 5 min read
  • by Priya Joi


Getting vaccines out to people living in remote areas can be a hugely complex task. You need to know where people live, where their nearest health centres and pharmacies are, how people can get to them – at times facing significant geographic barriers – and when patients are unable to travel, you need to know how to best organise vaccinators to reach everyone in need. This is where technology that can help; combining geographical and spatial data with health records and other medical information can be of immense value.

Geospatial technologies, including geographic information systems (GIS) software, global navigation satellite systems and remote sensing, can be important tools to inform the way vaccines are delivered. Digital maps that provide accurate information on the location of health resources compared with that of the target population and the geographic barriers between them, can provide valuable intelligence in a way that immunisation records alone cannot, and this can lead to more efficient planning for vaccination delivery. Moreover, the mapping of vaccination coverage information through GIS can act as a powerful advocacy tool for improved decision-making on populations at risk and on how resources are deployed. 

Geospatial data and technologies are still not being used to their full potential in low- and middle-income countries because ensuring the sustainable collection, management and use of such data at country level requires a long-term commitment to providing resources that may not be easy in these countries. Since COVID-19 has caused the pause or slowdown or immunisation programmes in many parts of the world, developing tools for data-sharing and collaboration, especially in remote areas, will be even more critical.

In a report published this month, Gavi researchers in collaboration with UNICEF and HealthEnabled, explored the use of geospatial technologies in immunisation programmes, particularly in polio and measles-rubella vaccination campaigns, to understand how we could integrate such technologies in the future.

Collecting geospatial data

Geographic information systems capture, store, organise, analyse and visualise data based on geographical locations. Much like in a library, where books belonging to specific genres would be organised accordingly, GIS can organise and overlay data depending on their geographic location, and whether they are near or far from each other. This can reveal relationships between geographic objects, and spatial patterns in variables that would be hard to detect otherwise. For example, such data can provide evidence of which villages are within 5 km from a vaccination delivery site and are therefore a manageable two-hour walk away. 

Spatial data that feeds into GIS are collected using a variety of methods. Remote sensing imagery, such as that provided by satellites, provides information on land surface features over large areas such as the location of buildings and roads, or land use type. 

Meanwhile devices capable of connecting to a global navigation satellite system (GNSS) – such as a smartphone – could be used to pinpoint the geographic coordinates of any location on Earth. Taken together, these technologies are powerful tools to analyse and model complex systems, such as vaccine delivery, and visualise outcomes, as well as provide compelling advocacy to support decision-making.

The different uses for geospatial data in immunisation programmes

Health system mapping is one of the most important applications of geospatial data with regard to immunisation coverage. It requires building complete and updated geolocation datasets of all infrastructures related to health care delivery, such as hospitals, clinics, pharmacies, supply chain warehouses and outreach vaccination sites. In addition, precise information is needed on the geographic boundaries of health districts and health facilities catchment areas. In many low- and middle-income countries, these data sets are incomplete and or not frequently updated. Cameroon and Somalia are two examples where such datasets have been built through training government personnel on the use of GNSS devices to collate this information. 

Mapping population distribution through geolocation of all inhabited places in a remote unmapped area by using satellites or GNSS positioning can help reduce the number of missed settlements, to pinpoint zero-dose children (who have not received any routine immunisations at all), under-immunised children (who have not received all routine immunisations) and the communities in which they live. Similarly, complex population estimation models when overlaid with satellite imagery and census information can provide better quality data on the number of children to be vaccinated in any particular area, which is a significant weak point of administrative data systems. This can improve equity in vaccine delivery. An underestimation of the need for vaccine supplies can also mean a greater risk of disease outbreaks if coverage is thought to be higher than it actually is. 

Health-system mapping and better information on population distribution can be combined to inform vaccine delivery strategies at the health facility and health district level – a process called ‘microplanning’. For example, in Nigeria, microplanning for polio vaccination resulted in 3,000 new settlements being included in operational plans. Here, GNSS devices were also used for near the real-time tracking of the movement of vaccination teams, so that effective coverage could be verified.

Collecting geolocated data on disease incidence can inform disease surveillance and trigger an outbreak response. Geospatial data can also be used to monitor campaign progress. In Malawi, for example, measles vaccination campaigns have used it to deliver real-time feedback on progress of the campaign as well as gather individual household data, including reasons for refusing a vaccine. 

Whether or not people can get to a health service in a timely manner can affect whether they will get vaccinated. Geographic accessibility modelling is used to estimate the time that people will need to get to a health facility, depending on modes of transport used locally and barriers encountered (e.g. river crossing), providing crucial information on gaps in accessibility that can reduce the use of services. Finally, geospatial analysis of vaccination coverage data from surveys can provide information on disparities in vaccination coverage within a country. UNICEF is working with countries to triangulate such data with routine administrative data to improve the quality of available information on immunisation coverage and equity for programme monitoring.