Department of Industrial and Systems Engineering, Rochester Institute of Technology, 81 Lomb Memorial Drive, Rochester, NY 14623, USA.
Health Care Manag Sci. 2012 Sep;15(3):188-96. doi: 10.1007/s10729-012-9200-4. Epub 2012 Apr 19.
Outreach immunization services, in which health workers immunize children in their own communities, are indispensable to improve vaccine coverage in rural areas of developing countries. One of the challenges faced by these services is how to reduce high levels of vaccine wastage. In particular, the open vial wastage (OVW) that result from the vaccine doses remaining in a vial after a time for safe use -since opening the vial- has elapsed. This wastage is highly dependent on the choice of vial size and the expected number of participants for which the outreach session is planned (i.e., session size). The use single-dose vials results in zero OVW, but it increases the vaccine purchase, transportation, and holding costs per dose as compared to those resulting from using larger vial sizes. The OVW also decreases when more people are immunized in a session. However, controlling the actual number of people that show to an outreach session in rural areas of developing countries highly depends on factors that are out of control of the immunization planners. This paper integrates a binary integer-programming model to a Monte Carlo simulation method to determine the choice of vial size and the optimal reordering point level to implement an (nQ, r, T) lot-sizing policy that provides the best tradeoff between procurement costs and wastage.
外展免疫服务是指卫生工作者在自己的社区为儿童接种疫苗，对于提高发展中国家农村地区的疫苗覆盖率是不可或缺的。这些服务面临的挑战之一是如何减少疫苗的大量浪费。特别是，由于开瓶后安全使用时间（自开瓶以来）已过，疫苗剂量仍留在瓶中，导致了开瓶后浪费（OVW）。这种浪费高度依赖于小瓶尺寸的选择以及计划外展服务的预期参与者人数（即服务规模）。使用单剂量小瓶可实现零 OVW，但与使用较大小瓶尺寸相比，每剂量的疫苗采购、运输和储存成本会增加。当更多人在一次服务中接种疫苗时，OVW 也会减少。然而，在发展中国家的农村地区控制实际到外展服务的人数高度依赖于免疫规划者无法控制的因素。本文将二进制整数规划模型集成到蒙特卡罗模拟方法中，以确定小瓶尺寸的选择和最佳重新订购点水平，以实施（nQ，r，T）批量策略，在采购成本和浪费之间提供最佳权衡。
