# Spatial Risk Analysis of Circulating Vaccine-Derived Poliovirus Type 2 (cVDPV2) in Nigeria
## 1. Introduction
Nigeria has made significant progress towards polio eradication; however, the continued circulation of circulating vaccine-derived poliovirus type 2 (cVDPV2) remains a major public health concern. Persistent outbreaks are often driven by immunity gaps, high population concentration, and uneven surveillance performance, necessitating targeted and data-driven responses.
Traditional tabular surveillance reports offer limited insight into where transmission risk is concentrated and how interventions should be prioritised geographically. Spatial analysis provides a powerful means of transforming surveillance data into actionable intelligence for immunisation planning and outbreak prevention.
This project applies GIS-based spatial analysis and interactive data visualisation to assess cVDPV2 risk at Local Government Area (LGA) level in Nigeria, producing a composite risk index and an operational decision-support dashboard.
## 2. Aim and Objectives
### Aim
To identify, classify, and visualise LGA level cVDPV2 transmission risk in Nigeria in order to support targeted public health interventions.
### Objectives
• Aggregate ward-level cVDPV2 case data to the Local Government Area (LGA) level and integrate population density to assess transmission potential.
• Develop a composite spatial risk index to classify LGAs by cVDPV2 transmission risk.
• Visualise and communicate high-risk LGAs through an interactive dashboard to support targeted immunisation and surveillance planning.
## 3. Data Sources
### Datasets Used
• Ward level cVDPV2 Surveillance Data
• GRID3 Nigeria LGA boundary shapefile
• Population Density Raster for under 5 years
## 4. Methodology
### 4.1 Spatial Data Processing (QGIS)
• Harmonise and clean all spatial datasets, ensuring consistent coordinate reference systems and standardised LGA and ward identifiers.
• Perform spatial j …