3 Urban Epidemics

Social Distancing has become the mantra of policy response to the 2020 Corona Outbreak. Economic forces have for centruries pushed people closer and closer together in urban agglomerations. The emergence of a major pandemic in the 21th century - although forewarned - obviously was not a risk factor considered seriously by these same economic forces - neither private nor public decisionmakers when promoting and allowing the construction of the great agglomerations.

Homo Sapiens was not made by nature to live in megacities. The corona outbreak is a piece of nature striking back as a reminder of the vulnerability of the artificial urban environment to the most basic of natural evolution - mutation of a virus.

Stier (2020) provides an empirical treatment of the relation between urban size and the speed of epidemic spread in the US during the 2020 corona outbreak. The main findings are:

  • faster spreading in larger cities

  • larger fractions of the population infected

  • more aggresive distancing needed

The virus is new, i.e. everyone is susceptible. The virus provokes a respiratory disease which makes transmission easy. The reproductive number \(R_{eff}\) seems to be higher than for ordinary influenza. Two factors determine how contagious the disease is: 1)length of the infectious period and 2) social contact intensity. Cities are the best breeding ground due to the high contact intensity.

The higher socioeconomic connectivity of larger cities in a fast urbanizing world makes containing emergent epidemics harder. But the density of socioeconomic connections in cities can also facilitate the spread of information, social coordination, and innovations necessary to stop the spread of COVID-19. This information and associated actions can easily spread much faster than the biological viral contagion. To fight an exponential, we need to create an even faster exponential! (Stier (2020))

So - the fight between Humans and Nature goes on! The bigger question - of course - being whether Humans should consider stopping creating such large [unhuman] agglomerations. There are many diseconomics to scale - epidemics being just one. Cities grow due to dominant economics of scale -i.e. benefitting the rich and powerful. The diseconomics are borne by others. Changing the current path does not seem easy - it goes to the core issue of Capitalism. This is treated elsewhere. Here we look into the more narrow theme of Urban Scaling