Cities are hotspots for COVID-19 outbreaks due to their high population density. In fact, between 2005-2019, population densities across the world’s cities surged 23 percent. These dense cities also tend to have large public transit networks and mobility sharing, all which make cities ideal breeding grounds for viruses like COVID-19. In the future, cities may need to respond by enforcing screening procedures, pedestrianizing streets and overhauling urban design in order to combat pandemics.