"Microbes that ignite pandemics are those whose evolution has adapted them to fill the ecological niches that we have prepared. COVID-19 flared up because it is suited to the society we have made.
"A world with nearly eight billion people, the majority of whom live in densely crowded cities and all linked by air travel, creates innumerable opportunities for pulmonary viruses."
The new coronavirus and the measures to suppress it have had their most devastating impact on mortality and the economy in large, densely populated cities that were previously the most dynamic parts of the modern economy.
Megacities including Wuhan, London, New York and Paris, as well as smaller primary cities such as Milan, Melbourne, Madrid and Barcelona, have all been hotspots of the epidemic.
Dense population and high levels of regional, national and international connectedness have made such urban centres exceptionally productive and successful.
But they have also fostered the vulnerabilities that the coronavirus has exploited, including overcrowding, intense social mixing, and reliance on public transport and aviation to move large numbers of people every day.
Britain’s experience has shown a clear correlation between age-adjusted death rates from COVID-19 and population density, overlaid by measures of poverty.
The highest death rates have all been in London and other metropolitan areas where population densities are far above the national average (https://tmsnrt.rs/2PQiKSR).
The highest rates of all have been in London boroughs with high levels of overcrowding and deprivation.
Brent (7,700), Newham (9,800), Haringey (9,000), Lewisham (8,700) and Tower Hamlets (16,200) all have population densities per square kilometre vastly above the average for England (432).
These boroughs are not just crowded but also poor, unlike other, richer densely-populated boroughs such as Islington (16,200), Kensington and Chelsea (13,000) and Westminster (12,400).
The worst affected areas outside London also exhibit relatively high densities combined with deprivation, including Middlesbrough (2,600), Salford (2,700), Birmingham (4,300) and Manchester (4,800).
London’s experience, mirrored in other megacities, confirms that COVID-19, like cholera and tuberculosis, has been fundamentally an urban epidemic fuelled by crowding and poverty.
Urban areas at the heart of the epidemic have a distinctive economic structure, including a services-dominated economy, much of it concentrated in central areas, and a reliance on public transport to move both workers and customers.
In the last census in 2011, half of those with a job in London said they used public transport to get to work, rising to 67% of those with jobs in inner London, and 84% in the City of London, the main financial district.
"Other conurbation areas in England and Wales do not come close to having London’s level of public transport usage," the UK Office for National Statistics wrote recently.
"For conurbations overall (excluding London), the level of workers arriving at work having used public transport as their main mode of travel was 15%." ("Coronavirus and travel to work", ONS, June 24).
"Rail and underground (rail) were the main modes for 38% of commutes to London workplaces, the share for non-London conurbations was 5%, for other urban local authorities 2% and for rural local authorities only 1%."
Coronavirus and anti-contagion controls have disproportionately disrupted public transport and especially rail and underground, ensuring the greatest impact has been felt in the capital.
Passenger journeys by car have recovered to around 90% of their pre-lockdown level. But journeys by rail and underground are still at less than 30% of their pre-epidemic level, according to the UK Department for Transport.
Urban economies tend to be dominated by service industries, which have been among the sectors hardest hit by the epidemic.
Britain’s real output was down 17% in June compared with the same month a year earlier, but the fall in services output (17%) was worse than in manufacturing (12%). The worst affected sector, construction, where output was down 26%, also tends to be concentrated in the fastest-growing urban areas.
The services sector includes both relatively labour-intensive, low-productivity, low-wage industries such as tourism, hospitality, food services and entertainment, and high-productivity, high-wage activities such as finance, insurance and law.
The former have been among the worst disrupted by lockdowns because of their reliance on face-to-face social contact.
The latter have been among the least impacted but have also seen the largest shift away from daily travel to central offices towards remote working, as habitual commuters try to avoid crowded public transport systems.
Employment in the worst-affected London boroughs is dominated by labour-intensive low-wage services such as retail, transport, health and social care, which have exposed the population to far-above average transmission risks, compounding the impacts of overcrowding and poverty.
The risks posed by the coronavirus are forcing all countries and communities to rethink how social and economic processes can be adjusted to reduce transmission risks, at least until a successful vaccine or other control measures are developed.
Politicians, journalists and other opinion-formers tend to be clustered in the largest cities, which colours the way they frame challenges and possible solutions.
But it is cities, particularly the largest, densest and most connected megacities, that potentially face the largest upheavals.
In particular, policymakers must work out how far to change the model of daily commuting to central offices, mostly by crowded public transport, in favour of remote working from the suburbs, or even outside the metropolitan area.
Cities must also contemplate how to restart sectors such as entertainment, leisure, the arts, accommodation and hospitality, all intertwined with tourism, that account for a high share of local employment.
And then there are the enormous amounts of hard capital (commercial and residential real estate, transport systems) and soft capital (businesses, cultural assets) that could be left stranded if there were wholesale changes to space use.
With so much at stake, in terms of both finance and health, cities are where the sharpest battles will be fought over the shift in work locations and how to balance re-opening social and commercial activities with continued suppression of the virus.
(Editing by Kevin Liffey) ((firstname.lastname@example.org))