Developing childhood vaccine administration and inventory replenishment policies that minimize open vial wastage

In the last century, many infectious diseases have been completely eradicated or significantly reduced because of childhood vaccinations. Ample evidence suggests that low vaccination coverage in developing countries is caused by vaccine stockout and high rates of vaccine wastage. Wastage occurs when a vaccine vial is physically damaged or exposed to extreme temperatures, or when doses from an open vial are discarded after their safe-use time expires. The latter is referred to as open vial wastage (OVW). Clinics can use single-dose vials to reduce OVW; however, such an approach is more expensive than using multi-dose vials. The focus of this research is to develop new policies that support vaccine administration and inventory replenishment. These policies are expected to reduce OVW, reduce the cost of vaccinations, and improve vaccination coverage levels in developing countries. This paper proposes a two-stage stochastic programming model that identifies an optimal combination of differently sized vaccine vials and the corresponding decisions that clinics make about opening vials in the face of uncertain patient arrivals. This work develops a case study with data gathered from Bangladesh. Experimental results indicate that using a combination of vials of different sizes reduces OVW, as opposed to the current practice of using single-sized multi-dose vials. Experimental results also point to simple and economic vaccine administration policies that health care administrators can use to minimize OVW. The model is solved using an extension of the stochastic Benders decomposition algorithm, the L-shaped method (LS). This algorithm uses Gomory mixed integer and mixed-integer rounding cuts to address the problem's non-convexity. Computational results reveal that the solution approach presented here outperforms the standard LS method.