Development of a COVID-19 Contact Tracing Application for a Local Government in Ogun State

Contact tracing during outbreak events in Ogun State has historically relied on manual processes that are slow, incomplete, and difficult to analyse at scale. This study describes the development of a Bluetooth-based COVID-19 contact tracing application for a local government health department in Ogun State, South West Nigeria. The application uses Bluetooth Low Energy (BLE) proximity detection to log contact events between app users, storing records locally and uploading pseudonymised exposure events to a central server upon user consent. The backend was developed with Node.js and PostgreSQL, and notification logic alerts users when a registered contact tests positive. Privacy protection was ensured through one-way pseudonymisation of device identifiers. The application was developed for Android using Java, with development spanning ten weeks using Agile methodology. Simulation testing using 30 devices confirmed exposure logging accuracy within 1.5-metre proximity. BLE detection rate was 94.6 percent under real-world indoor conditions. A 30-day community pilot in Sagamu LGA involving 400 registered users generated 2,100 exposure logs, with 12 positive test notifications sent. Community members reported high trust in the application's privacy protections. The study concludes that locally developed, privacy-respecting contact tracing apps offer viable tools for Nigerian public health outbreak response and recommends piloting the approach in the next disease outbreak event in Ogun State.

Keywords: contact tracing, COVID-19, Bluetooth proximity, Ogun State, public health technology