Facility location and multi-modality mass dispensing strategies and emergency response for biodefence and infectious disease outbreaks

Mass dispensing for medical prophylaxis and treatment of the general population requires rapid establishment of a network of dispensing sites and health facilities that are flexible, scalable and sustainable. In this article, we describe a systems approach to analyse mass dispensing of countermeasures, and present a set of powerful modelling and computational tools to assist in strategic and operational planning. Facility location models are used to determine the number of dispensing sites required. Our models account for variable population densities, the maximum distance individuals should have to travel, the types of private and public facilities available and the availability of critical staff to man the point-of-dispensing facilities (PODs). Large-scale simulation is employed to model the stochastic service and dynamic flow behaviour within PODs; and optimisation is interwoven to determine appropriate staffing levels for efficient operations logistics. A cost effective mass dispensing network for anthrax prophylaxis involving a metropolitan area with over 5 million people is presented. The study reveals that: (1) the sharing of labour resources across counties and districts is important; (2) the most cost effective dispensing plan across a region involves a multi-modality strategy, consisting of a combination of drive-through, walk-through and closed PODs, each operating at a throughput rate depending on the surrounding population density, facility type and labour availability; (3) the optimal combination of POD modalities changes according to various facility capacity restrictions, as well as the availability of critical public health personnel; (4) an increase in the number of PODs in operation does not necessarily increase the total number of core public health personnel needed; (5) optimal staffing is non-linear with respect to throughput; thus, the optimal staffing and throughput cannot simply be estimated using an average estimate; (6) there exists an 'optimal' capacity for each POD location, depending on the population, that provides the most effective staffing needs. The study also reveals that such computationally sophisticated decision support tools are invaluable to emergency managers. The tools provide flexibility to quickly analyse design strategies and decisions, and can generate a feasible regional dispensing plan based on the best estimates and analysis available, and then allow for reconfiguration of various PODs as the event unfolds. The type of disaster being confronted (e.g. biological attack, infectious disease outbreak or natural disaster) also dictates different design considerations with respect to the dispensing clinic, facility locations, dispensing and backup strategies, and level of security protection.