COVID-19 attack rate increases with city size

Andrew J Stier; Marc G Berman; Luis M. A. Bettencourt

In the absence of a vaccine, social distancing remains the only option to slow down the spread of the disease and arrest potential mortality. Governments around the world are now enacting aggressive policies, including "shelter in place" and emergency closures of all nonessential services, which carry severe economic and social consequences. For example, in the last week, the US Centers for Disease Control and the White House have recommended extreme social distancing in order to slow down the current outbreak of novel coronavirus disease 2019 (COVID-19) (5). However, these measures are less aggressive than what has been put in place elsewhere (6) . There is still a great deal of uncertainty as to how strong social distancing recommendations must be or how long they must last. Importantly, national and regional social distancing policies are likely to impact individual cities differently.