To address open vial wastage, the WHO has a multi-dose vial policy Epigenetics Compound Library chemical structure (MDVP) that permits vials of certain vaccines to remain open for up to 4 weeks so long as certain criteria are met regarding handling, administration, and storage [7]. Some local health programs may

feel that they are unable to meet these conditions (for instance, in rural vaccination clinics or outreach settings) and workers may discard open vials after each clinic day. With certain vaccines, the MDVP may not apply [4] and [8]. For countries and clinic settings that cannot comply with the WHO MDVP, there are two driving factors that influence open vial vaccine wastage: (1) the session size of a vaccination facility, and (2) the vaccine vial size [8] and [9]. The larger the session size (the more children who showed up for vaccination during one session), the fewer the overall remaining doses. One strategy that has been examined to help reduce open vial wastage is to lower the number of doses per vaccine vial [2] and [3]. A 2012 study found that in primary care settings in urban India, vial size is statistically significantly related to vaccine wastage [10]. While switching to lower dose vials might reduce open vial vaccine wastage, it will incur higher purchasing, manufacturing, storage and vaccine delivery

costs. Moreover, many new vaccines come at a higher Stem Cell Compound Library datasheet price per dose than traditional vaccines, and thus wastage is more costly [11]. A 2009 study found that the optimal vial size depends on country-specific wastage rates, and concluded that these critical data are missing for most GAVI eligible countries [12]. In 2010, Lee et al. [6] applied a mathematical model to capture the vaccine wastage and associated economic impact of different vial size strategies. Due to the lack of facility data in real-life

settings, the paper assumed that session size follows a Poisson distribution. Rolziracetam The paper emphasized that in order to calculate the expected wastage rate, one needs to first define the distribution of session size. No studies have since collected data on vaccine session sizes and defined a statistical distribution to generate open vial vaccine wastage as an output. In our study, we used session size data from four countries to develop a realistic statistical model of open vial wastage rates and their associated costs. We use the term “session size” in our study to refer to the number of children who arrive at a given vaccination session. There were two primary objectives to this study: first, to use session size data from four GAVI-eligible countries to understand country-level factors that influence wastage in open vials; second, to estimate the economic impact of switching to smaller dose vials. The Strategic Advisory Group of Experts on Immunization (SAGE) recommended inactivated polio vaccine (IPV) to be introduced to the routine immunization program by 2015 [13].