In 2012, the Federal Government of Nigeria launched the Saving One Million Lives Initiative aimed at expanding routine immunization to 87% coverage that will protect over 6 million children against vaccine preventable diseases such as measles, meningitis, polio, tetanus, hepatitis, yellow fever and tuberculosis . In 2013, the GAVI Alliance approved US$ 21 million to help improve vaccine supply chains . Despite several innovations and initiatives to optimize the supply chain and storage of health commodities in Nigeria, there are still known gaps in the supply chain in the health sector in Nigeria. Achieving a good coverage of routine immunization is almost impossible without the optimization of last mile delivery – especially in the hardest-to-reach places of Nigeria. Geographic Information science (GIS) techniques play a big role in the design and optimization of last mile delivery of vaccines down to Local Government Areas and health facilities in remote places. This presentation discusses how eHealth Africa has implemented FOSS4G solutions to enhance an effective vaccine delivery system in Kano State, Nigeria; the second most populated state in Nigeria using open source tools like OpenDataKit, QGIS, JOSM, OSRM. We also discuss the importance of OpenStreetMap and open data to replicating this in other countries.