question: We provide an overview of the design and analysis of a simulation model that was used in designing, refining, planning, and implementing the world's largest drive-through mass vaccination clinic in Louisville, Kentucky The Louisville Metro Public Health and Wellness department provided the H1N1 vaccine to 19,318 residents via a drive-through and a walk-up clinic over 1 5 days Almost two-thirds of the people vaccinated used the drive-through clinic The simulation model and its results helped advise the project commissioners about the feasibility of the drive-through vaccination It also allowed them to determine the proper layout and levels of staffing for efficient dispensing of the vaccines General observations made at the actual clinic and a comparison of those with the simulation model are presented Recommendations and shortcomings are discussed for improving the flow of the drive-through and the effectiveness of the data gathering, which could be helpful in future efforts With the entire world having to react to the COVID-19 pandemic and plan for protecting citizens against the novel coronavirus, the models we developed and the experience we gained could be helpful in administering COVID-19 tests to large swaths of the population quickly or dispense vaccines, when the latter becomes available