April 2, 2020

By: Ana V. Diez Roux, MD, PhD, MPH
Dean, Dornsife School of Public Health
Drexel University 

Lea la versión en español, publicada en el diario El País, aquí. 

Today over 4 billion people (more than half of the world’s population) live in cities.  Cities are growing rapidly even in parts of the world that were largely rural just a few decades ago.  People come to cities in search of better jobs, better services, better lives for themselves and their families. But cities can be good or bad for health depending on how cities are organized and governed. Today the COVID-19 pandemic highlights the impact of urban living and urban policies on health like never before.

Cities are, by definition, dense: a lot of people living together and interacting, socializing constantly. This is what gives cities their energy, their drive, their creativity. In the case of transmissible respiratory diseases like COVID-19 it is also why disease transmission can be accelerated in cities. This is what we have been seeing in recent days with COVID-19 in many cities all over the world. When case isolation and contact tracing—the initial public health approach to controlling outbreaks— becomes difficult because cases increase very quickly or are not easily identifiable (due to lack of testing or because disease can be asymptomatic), social distancing can become a necessary strategy. Social distancing means slowing or even eliminating close interpersonal interactions: one of our core needs as social beings and one of the cardinal features, for better or for worse, of city living.  

The grand experiment in social distancing in urban areas that we are seeing all over the globe today, from Philadelphia, to Naples, to Buenos Aires, is unprecedented. It is motivated by the threat of a viral disease that spreads rapidly from person to person and that although likely mild in most infected people can be very severe and fatal in a small but significant proportion. If transmission is widespread, even a very small proportion of severe cases can result in many deaths. Health care systems can be quickly overwhelmed resulting in even more deaths. There is an urgency to act, and a strong rationale for social distancing given the rapid growth of cases and the possibility of transmission from large numbers of asymptomatic cases. But the truth is that the consequences of this grand experiment (for health and for society generally) are at this point very hard to predict.

Social distancing, although justifiable in epidemic conditions, if sustained over long periods, can have dramatic unintended consequences for population health in cities. Social isolation affects not only mental health but can also impact the development and evolution of many other health conditions. The postponement of health care for other health problems (happening now all over the world as systems anticipate the expected influx of large number of COVID-19 cases) could dramatically affect morbidity and mortality from a range of chronic diseases. Staying home can often mean retreating to live in crowded and unhealthy housing. Many cities have high levels of poverty, and across the globe nearly one in three urban dwellers lives in a slum.

From the point of view of public health, perhaps even more important is the impact of social distancing on the social determinants of health. With businesses forced to close, layoffs will increase (we have already seen unemployment increase). Many workers lack sick leave and will lose income if they become sick. With children staying home some parents may no longer be able to work. Children who rely on schools for meals will lose this benefit. Workers involved in the informal economy (a significant proportion of jobs in cities of many low- and middle-income countries) will see their livelihoods disappear.

Cities are home to large social inequalities. These inequalities will be made even more visible and will likely be magnified by the COVID-19 pandemic and our response to it. It is too soon to know how COVID-19 is affecting different social groups but based on all we know about other diseases, it is likely that it too will eventually cluster, and be more deadly, among the most socially disadvantaged. They will have less access to timely and quality diagnosis and treatment (limited as treatment is today for COVID-19). They will have other health conditions that place them at risk for severe disease or even death. They will be more affected by delays in diagnosing and treating other health problems. And most importantly the socially disadvantaged will suffer the greatest adverse economic and social consequences of social distancing with as yet unquantified but likely significant health implications too.   

Even as COVID-19 justifiably draws all our attention, other health problems in cities still exist, other epidemics more silent than COVID-19 continue. And in many cities they are still claiming more lives than COVID-19: violence, traffic-related deaths, air-pollution-related deaths, deaths from preventable chronic diseases, preventable deaths in children, other infectious diseases like dengue (now an urban health problem) which have risen to epidemic proportions in many cities as consequence of global warming. In a paradoxical twist, pronounced reductions in air pollution (and presumably traffic related deaths) are occurring in major cities as transportation grinds to a halt. The impact of the COVID-19 pandemic on global travel will have major implications for reduced CO₂ emissions. All this shows, somewhat perversely, how human action drives these environmental factors and how human actions can change them.  

We have no idea how the social and economic changes we are seeing as a result of the pandemic and our response to it may affect violence or social unrest in cities (especially as restrictions and their economic effects increase). We do not know how this new and unprecedented power to restrict social interactions and movement may be used by authoritarian governments to exert social and political control. We cannot ignore this, or the other ongoing problems in cities, even during the COVID-19 crisis.

The COVID-19 pandemic, like other recognized and unrecognized pandemics, highlights the lack of coordination and planning in many of our government structures and makes even more visible the links between social inequalities and health. But it has also made clear how our health is connected to the health of our neighbors, how health in one country is inextricably connected to health beyond the border, and how decisive action to protect the health of the public in indeed possible. It is also showing how humanity can come together in times of crisis and do unprecedented things large and small, from sharing knowledge across countries to singing together across balconies.  Hopefully these lessons will bode well for how we handle not only this pandemic, but also how we address the many other ongoing public health challenges facing cities and protect our health and our environment in the future.