Modeling Vaccine Allocations in Rural Areas in Central Regions from Colombia

This paper addresses the problem of vaccination and distribution that has brought COVID-19 in rural areas from Colombia. Locations far from main cities are the last considered on vaccines supply taking into account the distance and the access. There have been territories where vaccines took to arrive more than 40 days, making it hard for inhabitants from these regions to protect themselves on time from the pandemic. With this in mind, mass vaccination programs are needed in order to get to each region and guarantee the demand coverage. For this reason, it was decided to plan the location and distribution of vaccines to 200 potential sites in five different departments in Colombia, by means of a linear model developed in GAMS software, taking into account demand parameters, costs and transportation distances in order to obtain information to define vaccination points with their coverage areas and the amount of vaccines sent to each site, considering the main percentage of vaccination according to the population of each department in order to supply a large part of it, prioritizing people who do not have any dose and to those whose health condition requires it. This paper proposes a mathematical model based on demand satisfaction, distances, and capacity to select potential vaccination centers. In this document, first, the state of art is presented regarding the different approaches that have been developed to address this problematic. Second, an explanation of the problematic is provided choosing five regions in Colombia, especially rural areas where access to vaccination is limited. Third, the parameters used like distance, costs of transportation and operational costs for each vaccine, quantity of demand, vaccination capacity, and development of the model considering the objective function and constraints is explained. Fourth, a MILP optimization model approach is considered, and the results are analyzed. Finally, conclusions are provided as well as future research. With the results of the model, a possible solution is obtained suggesting that a total of 101 potential vaccine sites are required to satisfy the demand in the regions contemplated.