Disease is an old companion to urban life. The golden age of Periclean Athens was arguably ended by the plague that struck that polis in 430 B.C.E.; the Bubonic plague hit Constantinople in 541 C.E. and derailed Justinian's attempt to reimpose the Pax Romana on the Mediterranean world. Yet during the century since the Influenza Pandemic of 1918-1919, our urban world has seen remarkably few massive outbursts of illness. During this more recent time period, humanity seems to have almost forgotten that cities are particularly vulnerable to contagion and that the urban health of the 20th century was built on massive investments in sanitary infrastructure, like sewers and aqueducts, during the 19th century.
Baum-Snow, Nathaniel, Edward L. Glaeser, and Stuart S. Rosenthal. "The Spread and Consequences of COVID-19 for Cities: An Introduction." Journal of Urban Economics 127 (January 2022): 103428.