New York has become the epicenter of the coronavirus pandemic in the U.S. As of this writing, it has about 40% of the confirmed cases in the country, much more than any other state:

The state has also had one of the fastest rates of increase. Part of that might simply be due to higher number of tests being performed; other states may have outbreaks that are as yet undetected. Part of it might be due to more international travelers introducing the virus at more points in February. But many commentators have zeroed in on another culprit: urban density.

New York City, with about half of the cases in the state, is far and away the densest large city in the U.S., with about 28,000 people per square mile as of 2016. San Francisco, in second place, has only about 18,000. Under normal circumstances, New Yorkers are crammed together in parks, on streets, at big events and in crowded restaurants, bars, cafes and offices. Land is at a premium, so indoor spaces and streets are small. Expensive and small apartments give people an incentive to leave the house and mingle.

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Then there’s the transit system. New York City has the highest public transit ridership of any big city, thanks in part to its extensive subway network. Crowded trains and buses cram people into small spaces where any cough or sneeze can spread a virus.

Density isn’t destiny when it comes to disease.

But although this explanation sounds plausible, skeptics note that Asian countries such as South Korea, Taiwan and Singapore have extremely dense cities and have suffered less severe outbreaks than countries anywhere else. This may be because of other factors — rapid high-quality public health responses, a culture of mask-wearing and so on. But it shows that density isn’t destiny when it comes to disease.

Another problem for the density theory is that coronavirus infections have tended to show up first on the outskirts of cities, not in city centers. California’s outbreak started in suburban Santa Clara county rather than San Francisco and is still more severe in the former. New York’s outbreak started in Westchester County, north of New York City. These epicenters are suburban areas that we don’t normally think of as being very dense. This suggests that social and professional networks, rather than random interactions on streets or in trains, are the main vectors by which diseases such as the coronavirus spread.

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Research suggests that urbanization does foster disease in developing nations, but it’s more often because of poor sanitary conditions and improper ventilation. Developed countries can have these issues too; one building in Hong Kong is believed to have spread the virus via unsealed pipes.

As for transit, some have claimed a correlation between train use and disease outbreaks. But evidence from Japan, where train use is ubiquitous, suggests that proper ventilation and masks substantially reduce infections and that the speed of disease transmission depends more on how much time people ride on trains than on how crowded they are. This means that extensive networks of fast trains that allow people to reach work more quickly could actually make transit less dangerous, provided the trains are well-ventilated. Notably, Singapore, Seoul, Hong Kong and Taipei, big cities where lots of people ride trains, have not had major outbreaks.

The evidence and the experience of Asian cities tells us that urban density alone doesn’t necessarily foster disease. But making cities safe against epidemics requires changes in both government and personal behavior. City governments must be efficient and proactive in providing and mandating sanitation and good ventilation — on trains, in buildings and on streets. This has to extend to low-income neighborhoods too, meaning that cities have to both focus resources on these neighborhoods and be willing to enforce regulations in those areas. For citizens, there’s a trade-off — greater government efficiency for greater citizen compliance.

In addition, people in cities need to change how they act. Fashion and social mores must adapt to allow widespread mask-wearing. People must develop strict sanitary habits regarding trash disposal, coughing and sneezing into the air or in crowded spaces.

Urban density is an important source of both economic productivity and quality of life. It’s also good for the environment. It would be a shame if Americans were to conclude from the coronavirus outbreak that density is dead and retreat once again to the sprawling suburbs. Instead, Americans simply need to realize that there’s a price to be paid for the joys of city life — efficient government, strong regulation and responsible behavior.

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©2020 Bloomberg L.P.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners or that of AXA IM.