The study, Lives and Costs Saved by Expanding and Expediting COVID-19 Vaccination, was led by researchers from PHICOR (Public Health Informatics, Computational, and Operations Research) at CUNY Graduate School of Public Health & Health Policy, the National School of Tropical Medicine at Baylor College of Medicine, and Johns Hopkins Center for Health Security. The team developed a computer simulation model of the entire U.S. and the spread of the COVID-19 coronavirus throughout the country. Using the model, the team could simulate vaccinating different proportions of the population at different rates with different types of COVID-19 vaccines. Like real people, each of these virtual people could become infected with the virus and develop different symptoms over time and, depending upon the severity of those symptoms, visit clinics, emergency departments, or hospitals. These in turn would have associated costs, allowing the tracking of various medical costs and productivity losses.