The first systematic worldwide campaign against vaccine-preventable diseases was the Expanded Program on Immunization (or EPI), started in 1974 by the WHO. In 2000, the Global Alliance for Vaccines and Immunization (GAVI) was launched specifically to extend the EPI program to the poorest countries in the world. Despite these efforts infectious diseases remain a grave, global concern and millions of children in low and middle income countries around the world remain at risk for diseases preventable via immunization. While a paucity of resources in poorer countries certainly contributes to vaccine-preventable deaths, many of the problems can be attributed to waste and inefficiencies associated with how the WHO-EPI vaccine distribution chains are designed and operated. The basic structure of the distribution network and its operation in virtually every country is identical and almost no thought has been given to fundamentally redesigning the distribution networks along the lines of other modern supply chain networks. This award supports fundamental research to address this critical issue by building and optimizing detailed mathematical models of the WHO-EPI vaccine distribution network. The proposed research will benefit society by providing alternatives that could fundamentally transform the way life-saving vaccines are distributed and administered around the world. It has the potential to improve the efficacy of vaccine distribution networks and enable millions of additional vaccinations annually around the world, resulting in reduced public health costs and saved lives.
A typical EPI network is designed as a four- (or occasionally, three- or five-) level hierarchical structure with strictly arborescent flows emanating from a single source node. The network is supplemented by flows from a subset of nodes in the network, to represent ad hoc outreach sessions to remote locations. This research will develop mathematical programming models to (1) permit any type of flow (rather than just strictly arborescent flows), while also being able to incorporate any domain-specific constraints on flow, (2) consider vaccine flows in the context of supply chain cold storage and transportation resources, (3) allow for country-specific operating policies to be adopted into the design, and (4) account for outreach activities that supplement static immunization facilities. The proposed network and integer programming models will capture the unique objectives, tradeoffs and constraints inherent in vaccine administration. The models are not simply an application of existing theory, but rather, novel extensions of the general supply chain network design literature to the unique domain of vaccine distribution networks.
