Modeling the WHO-EPI vaccine supply chain in low and middle income countries

The enormous economic impact of diseases has drawn global attention and controlling diseases through a vaccination program is one of the highest priorities in healthcare decision making. However, successful implementation of vaccination programs must also consider distribution network design and logistical feasibility. In this research we address this issue via three broad contributions. First, we develop a generic mathematical programming model of the WHO-EPI vaccine distribution network in low and middle countries, and adapt the model to answer actual vaccine logistics questions such as assessing the feasibility of new vaccine introductions, changing the distribution network design, and changing the vial size of an existing vaccine using the West African country of Niger to illustrate this. Second, we explore integrating vaccine distribution decisions with immunization policies by developing a framework for linking the vaccine supply chain model with a disease propagation model. The framework is used to assess measles interventions in Niger in order to help policy makers decide on an appropriate vaccination policy. Third, we address the significant challenge of increasing the clinic visit rate, especially in areas with limited health care resources and high-risk populations. To do this we explore the application of passive cold devices for vaccine delivery at remote vaccination sites. Such mobile devices are easy to deploy at locations that are off the electricity grid or have an unstable energy supply, and they can also be used to support outreach vaccinations to families in rural areas. We develop a computational model to evaluate the cost effectiveness of different device designs for vaccine delivery in real world distribution networks. We also conduct sensitivity analysis to determine which design is most robust with respect to fluctuations in cost performance.